Whatis - Manage & organize your team's knowledge straight from Slack
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Slack-News - Read news from multiple sources within Slack by just typing
Slinky - Your slack links — organized!
Slack It - A bookmarklet to share links in Slack with one click
Obie.ai - Access knowledge quicker without leaving Slack