InviteRobot - Instant subscription for paid Slack communities
Spectrum - Browser-based app to visualize the frequencies of an audio file.
SlackPass - Subscription access to anything with Slack
Treadie - Create your own micro-social network for topics
Magik for Slack - Magik enables founders, marketers & community builders to create the community experience they never knew was possible.
Roomvine - Chatrooms for real life venues, neighborhoods and events