Slack News Feed - Get the top posts from every Slack chat you're in.
Slinky - Your slack links — organized!
Slack-News - Read news from multiple sources within Slack by just typing
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
SlackScreen - Full screen public Slack channel display
Kifi for Slack - Get links messaged on Slack in Google Search results