From 2012 to Feb. 2017, the service has moved from 17,000 users to 5 million. That's especially amazing since it started out as the messaging system inside a video game that didn't get off the ground.
Slack's been called an "email killer"; we use it here at PCMag for that very reason (alongside Asana, Quickbase, and Google Apps), and it works. If you're not sure what it's all about, here's Slack's own video intro to the service.
If you're not a corporate titan with a big team, Slack can still work for you. Anyone can create a team for free, but gratis acounts are limited by how many services you can integrate (10) and how many messages you can store (10,000). At that level, it works for families and groups of friends—especially those already familiar with Slack from work.
Of course, if you pay, you get unlimited storage and integrations, with a per-user price that starts at $6.67/month.
Slack Technologies, the privately owned company behind the software, is riding high on its growth; it's never made a dime but has raised millions of dollars in funding, with another half-billion dollars just this June. Amazon is rumored to be coveting ownership of Slack and could pay $9 billion. It's a Slack world, we just message in it.
But we could be better at it. There's a lot of great stuff under the hood of the Slack system. Read on for all you need to know to get the most out of it and become the Slack-guru of your office.
(Note that on the following slides, many tips and links simply won't work if you don't have a Slack account, in particular a paid Slack account for your team; if you do, most will append your active teamname to the front of the URL. Those for owners/admins won't work unless you have that level of access.)
Download the App
You might think of Slack as a cloud-only service, accessed via the browser. And that's a more than viable way to handle it. However, Slack has the obligatory mobile versions for iOS, Android, and even Windows Phone, plus a full set of desktop apps for Mac, Windows, and Linux (Ubuntu or Fedora). Do you need the separate install to use Slack on the desktop? Absolutely not—it's essentially a browser pane anyway. But if you like to keep operations separate, so Slack won't crash if your browser does, this is a great option. No matter how you access Slack—mobile, desktop, browser—all the messages are always in sync.
Since Slack is all about messaging, that means using the keyboard. Naturally there are plenty of keyboard shortcuts to get the most out of your Slack-age. If you want quick access to the list, just hit Ctrl and the slash (Ctrl+/) on Windows, or Command+/ on Mac. It'll pop up instantly. You can also type /shortcuts or /keys in any channel.
Integrate Awesome Apps
What's a platform today without apps? Nothing! Thus, Slack has a plethora of third-party apps that can work within its confines to make life easier. Almost any user in a Slack team can add apps with a click of the "Add to Slack" button (with some restrictions, typically made by the team owner/admins).
At PCMag, we're fans of Giphy, Growbot (for celebrating team members), Google Hangouts (well, some of us are), and Chartbeat (for noticing spikes in traffic on the site). Apps you have heard of that work with Slack: Dropbox, Asana, Box, Google Drive, Skype, MailChimp, Twitter, Wunderlist, LucidChart, and Trellow. The apps directory is also the place to find extra "bots"—chat bots written specifically to communicate with Slack users and frequently help out with tasks.
Master the Slash
Shortcuts are great, but to access Slack's full power, type a forward slash (the one on the question mark key) in the message text box. What pops up is a full list of the commands at hand, everything from searching for apps to checking the weather. Many depend on app integration (see the previous slide), but there are several native Slack slashes you should know for everyday use.
/away—toggle your status to away (or back)
/collapse—collapses all the attached files in a channel (use /expand to see all)
/dnd—do not disturb. You should add a time description for the DND session to end. For example, add "30" and Slackbot assumes 30 minutes.
/feedback—send a message direct to Slack, the company
/invite—ask a specific user (via @ mention) to join a channel
/leave—Leave or unsub a channel (also use /close or /part)
/msg—quickly send a message to a user (/dm does the same thing)
/mute—stops notifications in the current channel/group or from an individual user
/open or /join—type the name of a channel to get access
/rename—give the current channel or group a new name
/who—see who's in the current channel/group
Perhaps the most important of all slash commands: /shrug
Set Slack Reminders
It's easy to get lost in a sea of Slacks; keep tabs on important messages or set reminders for yourself and other team members with the /remind command.
For personal reminders, go to your direct message channel and type "/remind @[your name]" followed by whatever you need to remember and when (/remind @eric to submit expense report tomorrow)
There, you can also add reminders for specific team members ("/remind @dan to change VPN password in 3 months"), which will pop up in their slackbot channel at the selected time. Or remind a whole channel using the hashtag ("/remind #party-committee to buy balloons on 7/3/2018").
You can't set them for user groups. Guests can't set reminders for others, just themselves. Recurring reminders are an option; Slack will recognize the syntax of you saying "on Tuesdays" or "every Tuesday" or "the 5th of every month," for example.
If you want a reminder about a specific message you've already received, hover over it, select the Show Message Actions menu () and select Remind me about this. You get five options for reminder time frame: in 20 minutes, 1 hour, 3 hours, Tomorrow, or Next week.
Want a list of all reminders? Type "/remind list." It'll give you a list of all past reminders as well, which you can delete.
Keep a Message Unread
Sometimes, you can't address what someone said in the moment. Make sure you don't forget. It's easy to mark a message as unread in Slack. Click it while holding down the Alt key in Windows, or the Option key on the Mac. On mobile, do a long press—hold your finger on it—a menu pops up that includes the option to mark it as unread. (On mobile, the long press is also how you copy text, add a reaction emoji, or star a message.)
Quickly View All Unreads
At the top of the left menu on the desktop version of Slack you'll see All Unreads—and it'll be bold if there are unread messages. Or click Ctrl+Shift+A to jump to it. Click it and you get one page full of all your unread messages, which you can peruse at your leisure. The top will show the Highlights—the messages Slack believes you'll find most important. As you view All Unreads, you can use the right and left arrow keys to jump from channel to channel represented, or just hit the R key to mark everything in that highlighted channel read (or toggle it back to unread). If you never want to see the All Unreads in the menu, go to Preferences > Advanced > Channel List > Turn on All Unreads and uncheck the box.
Clear Every Single Unread
For some reason this keystroke doesn't make the quick-list of Slack keyboard shortcuts you get when you hit Ctrl+/, probably because of its incredible might. But here it is: if you've got a lot of unread message and notifications you wish to ignore in Slack, on the desktop type Shift+Esc. You'll get a pop-up warning telling you quite simply you're about to mark everything as read. Check a box in the pop-up warning and you'll never see it again, putting Shift+Esc on the fast-track to keeping you at Slack-box Zero.
Only View Your Activity
All Unread is great but can still be unwieldy with a big team making lots of commentary. If you want to see only what's pertinent to you, click the @ icon at the upper right of the desktop and a new pane opens called Activity. This is the spot to see all your most recent mentions, reactions, and key words. Click the @ again or the X at top of the pane to hide it.
Powered Up DND
Do Not Disturb has some more powerful settings than just a per-channel/group amount of time using /dnd. Set an overall DND by clicking the bell icon at the top of the sidebar, and select an amount of time, from 20 minutes to 24 hours. Click the Do Not Disturb schedule to set not only the notification settings, but also a window of time—say midnight to 7am every day—when you'll never get Slack notifications. (Don't take your work to sleep with you, people.) Kind bosses who own or administrate your Slack team can set default DND hours for the whole team in Team Settings.
Speak to Slackbot
Think of Slackbot as the Siri of Slack—except it's not something you talk to, just chat with. The company calls it "your assistant, notepad, and programmable bot." Select Slackbot in the sidebar and start typing. It's a scratchpad for mastering your Slack-ness—go ahead and try slash commands, shortcuts, etc. It pops up in other channels when needed for your interaction with Slack or third-party apps. Drag files to Slackbot for your own personal storage on the service—they're searchable, but only by you. Type /remind me to [something] at [time] and you get an instant reminder at the time specified; or substitute an @ mention to send the reminder to someone else. If you say random things to Slackbot, you'll get replies. Slackbot is your friend.
Customize the Bot
For better or worse, you can program Slackbot to respond to certain words or phrases with its own words or phrases. Just go to slack.com/customize/slackbot and get customizing (keyword on the left, Slackbot response to the right). A good example is, if someone types "wi-fi password," Slackbot replies with it.
This is also a perfect spot for office jokes. Our most-used Slackbot customization is a public "gesundheit" wished to our most sneeze-prone editor. Replies can include images or animated GIFs or YouTube videos; simply insert the URL in the reply field. Note, any team member can create, edit, or delete anyone else's Slackbot customization—but owners/admins can curtail use of Slackbot Responses entirely in the Team Settings.
Get Notified of Highlight Words
A lot of messages can get sent in just a few hours on Slack, and you can't necessarily read them all. However, Slack can notify you specifically when pre-selected words or phrases are used. For example, if you're in charge of expenses, it alerts you when the terms "expenses, reimbursement, travel, T&E," etc. are used by members of the team. Set this up in your Slack Preferences.
Access Preferences on the desktop by clicking your name in the upper right, or on your avatar picture, or typing /prefs. In the Notifications tab, select Notification Settings. Scroll down to My keywords. In the box, enter a bunch of words or phrases separated by commas—any term you want to be on the lookout for, even if it's posted in a channel you're not subscribed to. Fine tune it if you get too many notifications. Scroll up on that page to set Slack to notifications for "Only direct messages and highlight words."
Adjust Channel Notifications
You can set global notifications, but they'll tend to be overwhelming. Instead use individual notification settings for each channel or group to which you subscribe. (Remember, a channel is preceded by a hashtag (#) and is accessible by everyone; a group is a private grouping of select people, with a lock icon).
To adjust, you have a couple of methods on the desktop. Go into a channel/group, click the name at the top, and select "Notification preferences." The pop-up will let you set different notifications for mobile or desktop (Activity of any kind, mentions/highlight words, or nothing), suppress when people use the @channel or @here mentions, or mute the whole thing. (Mute means you stay subscribed without any notifications of new activity, whatsoever.)
You can also go to Account Notifications. Scroll down to get channel specific settings for every channel in a handy grid.
Minimize the Noise
In the same way you want to minimize notifications from Slack, you may wish to customize the sounds it emits. Visit those same Notification Preferences to make batch changes—one change impacts all channels—or make changes individually for each channel by clicking the channel/group name. A batch muting means no sound or pop-up notifications on screen. But you can also change the sound alert alone. At the top of that Accounts page and the Notifications Tab, under Desktop Notifications and Mobile Push Notifications, keep the notifications but change the sound. That includes the option to choose "none" so there's a notification with no alert noise at all. (Unfortunately, you can't pick a different sound for each channel/group.)
Set a Default Emoji Tone
You've probably worried about this for years: what if you're using an offensive emoji skin tone? You should make sure your :thumbsup: or :middle_finger: best match your complexion, even if you're a jaundiced Springfield citizen from The Simpsons. You do that by hovering over a message, selecting the Emoji menu, then hovering again over the hand icon at the bottom of the menu. The words "Emoji Deluxe" should appear; click the hand and you'll see all six available skin tones. Pick the one that's right for you.
In the future, as you type in an emoji code that involves a hand, like :fist:, you'll see the choice default to the color you picked, such as :fist::skin-tone-3:. (The yellow hands don't get the extra words, they're the default skin-tone-1.)
iOS users get the default skin tone they already used on select emoji; Android users can go into Slack's Settings > Advanced to find Emoji Deluxe to set a tone.
There is currently one hand gesture that has all the skin tones, an "inclusive thumb" that changes color via a constant animation–:thumbsup_all:. Give it a try.
Emote with Homemade Emoji
You get access to a full slate of emoji in Slack. Type a colon, a description term, and another colon (:[term]🙂 to pull one up; Slack will auto-complete as you type in a description. They're great not only in a message, but also as the reaction to messages—click the Add Reaction button (a smiley with + sign) next to any message in Slack to use one.
The current slate of emoji doesn't cover everything. Here at PCMag we have found a need for many more emoji, with names like :bb8:, :costanza:, :freddykrueger:, and :barf:. Each of these had to be created by a member of the team, which anyone can do by visiting slack.com/customize/emoji. The user picks a name, uploads a square image smaller than 128 by 128 pixels, and the new emoji becomes part of the team's reaction arsenal. It even works with animated GIFs, as long as they're small enough (under 64K in file size). You can find a wealth of emoji to try yourself at Slackmojis.
Forward Email to Slack
Email isn't quite dead yet. Until it is, you can forward emails you receive directly to a Slack channel, all of which have their own email addresses. To create one, integrate the Email app for Slack. Once it's integrated, scroll down and click "Add configuration" to create an email to send directly to a channel, a group, or even an individual user inside Slack.
The email generated will look something like this: [email protected][teamname].slack.com. Give it a name that will come up in Slack, like "Newsbot." You can also assign it a profile pic, so that the "Newsbot," for example, gets a distinctive look. The pic can be an emoji, or an image you upload
Next, go into your email program of choice, create a contact name with that email address, but give it an alias like "Slack Newsbot" so it's easy to find as you type in the send field when forwarding, or for creating a filter to auto-send messages to the channel/group/user.
Quickly Jump to New Conversations
You may have a metric butt-load of channels, groups, and individuals to message in Slack. Jumping among them without using the mouse can speed things up. Push Ctrl+K on Windows, or Command+K (or Command+T) on the Mac desktop: the Quick Switcher comes up. Type in the name of the channel/group/individual desired and hit return to access it quick (thus the name). If you're on a mobile device, swipe right—there's Quick Switcher search box at the top.
Customize the Welcome
When Slack is loading, a pre-set message will display. When the team is tired of the good ol' "reticulating splines," members can infest Slack with new quotes, messages, or tips to show during loading. Insert them at slack.com/customize/loading. It's not anonymous; the text will be attributed to the team member who added it.
Activate 2-Factor Authentication
Hackers abound, and they might not mind getting access to your Slack account. Turn on two-factor authentication ASAP—it will require you to enter a code sent to your mobile phone to gain access on a new PC. (Read more about 2FA here.)
Go to slack.com/account/settings#two_factor and click the setup button. After you enter your password, you get two choices: receive the code via SMS text messages, or use a smartphone app like Google Authenticator or Authy. Even if you pick the app, you get the option to enter a backup mobile phone number. After, you'll need to re-sign in to Slack everywhere, with codes at hand to get full access. Owners/admins can go into Team Settings > Authentication and require team-wide 2FA if desired.
Repost a Message
Sometimes, a post is worth revisiting, even if it's not worth pinning. Find the original post you want to share again, and on the desktop, right click on the time stamp (or click the ellipsis menu next to the message) and select Copy Link. Then paste the link in any channel/group or to an individual. The link will expand to show the full original message in your Slack archives.
Chat with Slack via XMPP and IRC Client
Are you more than happy with the chat client you've got? If it supports XMPP/Jabber (like Pidgen) or IRC, then head over to slack.com/account/gateways and get all the deets needed to set that up. Note that reading messages in these clients will not get them marked as read—Slack can't tell if you read the message, nor will you see edited messages, only the originals. Plus, you can't use the slash commands. But if you must use those XMPP/IRC clients, you can.
Invite Outside Users
A typical Slack team can be identified by the company domain name—for instance, you set up the service to recognize a sign-in from anyone using a preset domain, like pcmag.com. That keeps outsiders at bay. But sometimes, freelancers or contractors need access. In that case, the owners/admins of the Slack team have the option to invite people.
Go to the slack.com/admin/invites page or navigate to Team Settings > Permissions. Invites require the full email, first name and last name of the person. That person gets either a restricted account with limited access to channels/members (they get charged like a regular member), or a single-channel guest account (up to five free guests are allowed per paid-for team member). Restricted and single-channel users can be changed to one or the other any time. Admins have the ability to limit just how long guests can remain, setting a deadline for their account to go buh-bye. Both guest and admin will get a warning a couple days before that happens.
Up Arrow to Edit
If you learn nothing else in Slack, learn this: you can edit messages. Of course you can click the "Show message actions" menu on any message you wrote to edit it (pictured above) but this is much easier: click the up arrow on the desktop keyboard immediately after you post. You'll instantly be placed in edit mode. In fact, this works to jump to your last message even if a bunch of people in the channel posted after you. (You typically can not edit a message after a day has passed, but admins can change that in the Team Settings.) Edited messages are marked as such, and owners/admins can turn off the ability to edit in Team Settings.
If you'd prefer to use the up/down arrows to cycle through the history of what you've written in the channel/group, check that setting in View Preferences (type /prefs) > Advanced > Input Options and check the last option. Then a Ctrl+UpArrow keystroke will get you into the quick edit mode.
Enrich Your Text
As you type in the Slack desktop interface, you'll see a few subtle, gray commands below the compose box. They're reminders of the codes to put around words to achieve rich text. Here they are:
bold from *bold*
italics from _italics_
strike from ~strike~ [that's the tilde character to the left of the 1 key; on mobile, click numbers then go to symbols (#+=) and it's on the second line]>indent one line
>>>indent all following lines
`code blocks` [use the "backtick" character on the same key as the tilde (~); on mobile hold down the single quotation mark]“`code blocks for all following lines.
You can see what code block text looks like above—colored text in a box. When you need a new line, hit Shift+Enter.
Post vs. Message
Slack is a messaging app by nature, but it's also got the capability to handle more detailed, collaborative items called Posts. Simply typing in a channel/group's text box creates a standard message, meant to be short and to the point. To make a Post, click the big plus sign (+) next to the text box and select Post. A pop-up screen is generated; it looks like a blog composition interface. Click the paragraph icon to bring up text settings, like creating bulleted lists or inserting headlines or even make a check-box task list. Rich text support means you can bold, underline, strike, block code, etc. without using the shortcuts in messages. Plus, you can insert hyperlinks.
Create Text Snippets for Reuse
Snippets, a little segment of text for re-use over and over by multiple members of the team, are one of Slack's best features for programmers. They rock for coders by supporting a number of programming languages—Fortran, C, C++, Cold Fusion, AppleScript, Ruby, Python, to name just a few—as well as good ol' Plain Text and HTML and XML. To create a snippet, click the + sign next to the message block, and select "Code or text snippet."
Sign Out Everywhere
Did you lose a device that's logged into Slack? Use a public PC and forget to sign out? Go to the desktop and sign out of every other device and Slack community you're currently using with one click. Click your avatar and select Account Settings (gear icon) on the right. On the Settings tab, scroll down and click the yellow button to Sign out all other sessions.
Notify Everyone (Occasionally)
Using @everyone in a message literally alerts everyone on the team, even if they don't subscribe to the channel or group you've entered it in. @channel or @group can be used in select channels/groups, naturally, so only channel/group members get notified. @here only alerts those who are active at that moment in the desktop app (it doesn't notify mobile users).
Use the @everyone and @channel alerts as little as possible or you risk being annoying—don't be the Slack user who cried wolf. Team Owners/Admins can go into Team Settings > Permissions > Messaging Restrictions and increase the warnings that come with using them.
Look to the Stars
Star messages to remember them. This is a great way to build a to-do list based on messages received in Slack. Mouse over the message and click the star next to the time stamp; on mobile, long press on the message and select "star message" from the pop-up menu. Later, access all the starred messages by clicking the star icon at the top-right of the screen on desktop or when you swipe left on a smartphone.
Star an individual person, group, or channel and they will show up at the top of your sidebar for easiest access.
Pin Important Messages
There's a difference between starring and pinning. Stars are just for you. Pins are for everyone. Pin a message in a channel to call attention to it, or make it easily accessible in the future, by everyone. Hover over a message (or long hold on mobile) and select "Pin to this conversation." To access pinned items, click the split-pane icon at the top of a channel/group to access the right sidebar; one of the features will be Pinned Items. This is also where you can unpin an item. (You can't access pinned messages on mobile.) There's a limit of 100 message/files pinned per channel at a time.
Call for a Video Conference
After a few years of working only with third parties for video conferencing, Slack finally launched built-in voice calls, video conferencing, and screen sharing. The latter two features only work on Mac and Windows desktops, in the download or the Web interface. Mobile and Linux users can only do voice. All desktop calls, be it voice or video, require the Google Chrome browser for now.
To start a call, either open a direct message window with the person and click the phone icon at the top. A pop-up screen will display call status, and give you icons to click to start video or screen sharing .
If you're in a channel, click and you'll be asked who you want to confirm. As many as 15 channel members can hop into the conversation, and again, Windows and Mac users can go video. Admins have the ability to enable or disable the call icon in Team Settings under Calls, and can even set it to only use a third-party service.
Narrow Your Searches
Slack archives everything the team says (in the paid versions); that archive might be useless without a decent search. The search box sits at the top of the Slack interface. The minute you click into it on the desktop or browser, it displays modifiers to help get specific results. These are the options:
from:[username]to:[channel or username]in:[channel or username]after:[date]before:[date]on:[date]during:[month/year]has:[star]If you have channels/groups you know you'll never want to search, type /prefs and go to the search tab. In the box provided, list the channels to exclude forever.
Instantly Slack Webpages
Slack itself is a Web app—you can use it entirely in your browser. Make Slack use easier in the Google Chrome browser with the add-on #Clicky for Slack. It puts an icon on the toolbar that makes sharing Web pages to channels and groups, searching, or getting notifications all a browser-based breeze.
If that's a bit much, there's a simple bookmarklet for sharing pages to a pre-picked channel/group with a single click available, too. Neither is supported by Slack.
Integrate with Automation Services
We never get tired of recommending IFTTT, a five-star tool for integrating web services. Naturally, Slack works with it, offering up recipes that can post to the Slack channel of your choice when things happen, such as an email arrives, a picture goes on Instagram, the company gets a Twitter mention, the weather changes, etc.
IFTTT isn't the only game in town when it comes to integrating web services. Zapier also rates high with PCMag editors, and take a decidedly more business-oriented approach, making it a perfect fit with Slack. With Zapier's Zaps (like IFTTT's recipes), let actions in Slack trigger other things—like having Slack automatically welcome new team members, notify the team when new channels are added, or copy (cross-post) pertinent messages between channels. Slack is also on the more mobile- and IoT-oriented automation service Stringify.
The Admin Kick
Sick of a particular person using up all the air in a channel or group? Slack Team Owners/Admins have power, as do the creators of groups. They can type /remove or /kick and the name of a user they want to disappear, making it look to others as if that user has left the channel.
Ask Admins to Hide Emails
If you're not keen on having your email address in your Slack profile, well, tough luck, Chester. It's required, and everyone else in the team—even single channel guests—can see yours. If you think it's a problem, check with your admin for the team—they can go into Team Settings and go to Email Display and toggle the requirement off or on. (You'll still have to enter it, it just won't be on display.)
Color Me Slacked
Designers, need to share some six-digit HTML color codes and wish you knew what it looked like? Post it in Slack with the leading hashtag, like #F77761C, and you'll see a little color swatch appear next to the post.
Belong to Multiple Slack Teams
When you join Slack, it's not just one account and that's it for life. You can belong to multiple Slack teams—say multiple groups at the office, or among multiple offices, or Slacks for work and home and friends. Switching is pretty easy. On the Desktop, hit the Team Menu (click the name of the team at the top of the left sidebar) and select "Sign on to another team." Enter the other team's name, and continue on. If you're on the Web, enter [teamname].slack.com. You'll have to enter your email address and password, of course.
On mobile Slack, swipe right, then right again, and click the + at the top next to Team to sign in to another team, or create a new team from scratch. Once you've signed on to multiple teams, the app will show icons for each on the side for easy switching.
Add Your Status
In the long overdue department: Slack finally added the ability to list your status, say "going to lunch" or "at the doctor" or "not willing to chat right now." Click your name on the desktop version > Set a status. On mobile, tap the triple-dot More menu () on the top right > Set a Status. There are five pre-set options (In a Meeting, Commuting, Out Sick, Vacationing, and Working Remotely), or create your own.
Status can also include emoji, which some people keep active all the time to gussy-up their name in the Slack list. Other team members will see the emoji, or just a speech balloon next to your name; hovering over the balloon reveals the status. It won't go away until you change it manually.
Thread the Messages
Part two of the overdue department: Slack finally added threaded messaging, something most chat systems have had for years. That means that a tangent conversation can be had in a channel with all the replies staying in a single thread, without necessarily bothering everyone else who subscribes to the channel. To start a thread, you hover over a message and in the pop-up menu select the word balloon icon for "Start a Thread." Any replies in a thread don't notify members of the channel, unless the specific users are mentioned. Users can see all their ongoing threaded messages across all channels by clicking All Threads in the menu, even on mobile.
Change the GIF Rating
Giphy is the first name in finding animated GIF images to share online; the integration the app has with Slack is second to none. Type "/giphy" and a subject, hit return, you get a pretty spot-on image inserted at random. However, your access may be limited. Giphy images are rated like movies from the MPAA, from G up to R; chances are you're only seeing PG-13 or lower. You have the option to go R or even "All" so the entire Giphy library is available, even stuff that's NSFW.
To change it, go to slack.com/services, click Giphy, make the selection, then click Save Integration. Only go unrestricted if your entire workplace is okay with that kind of thing. You can also set the ratings for other animated GIF apps for Slack, like RightGIF and SlashGIF.
Customize the Icon
Owners and Admins can add a little color to the Slack interface by creating an icon specific to the team. This is especially handy as an identifier if users belong to multiple Slack teams. A quick visit to slack.com/customize/icon to upload an image (measuring 132 pixels square or larger) is all it takes.
Message as Someone Else
Want to post not only anonymously, but also in a famous persona? The Slacker tool, which also works with HipChat, allows it. Sign in with your teamname, pick a character, type a message, pick a channel to post to (it won't work with groups or direct messages), and boom goes the dynamite. Everyone will think they're being stalked by HAL-9000, ordered by Captain Picard, or not talking about Fight Club with Tyler Durden. Make your own character persona if you want.