Madsounds - It’s like Discover Weekly, but daily.
Google Drive to Slack - Slack notifications whenever you work on Google Drive docs
Pyro - Spotify music voting for parties
Kissflow - Kissflow is a workflow tool & business process workflow management software to automate your workflow process. Rated #1 cloud workflow software in Google Apps Marketplace.
MisterJack - Make and share playlists
Heymarket for Slack - Text and Facebook messaging from Slack