Memonia - Automatic knowledge discovery and sharing for Slack
Slack News Feed - Get the top posts from every Slack chat you're in.
Whatis - Manage & organize your team's knowledge straight from Slack
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.