Clearbit for Slack - Send all signups directly to a Slack channel
Slack Overflow - A programmer's best friend, now in Slack.
Photostash - Automatically save your pictures from Slack to Gdrive
ask-stack - Get answers from Stack Overflow directly in the Atom editor
Slack It - A bookmarklet to share links in Slack with one click
Stack Overflow for Teams - Everything you love about Stack Overflow in a private space.