Slack News Feed - Get the top posts from every Slack chat you're in.
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Top Daily Hunts in Slack - A simple, fast way to browse news within Slack
Slinky - Your slack links — organized!
Slack It - A bookmarklet to share links in Slack with one click
Paperbot (Reloaded) - Slack meets Pocket