Parallel - Listen to music with friends over Spotify at the same time
MixTape - Home of MixTape, an OSX application for creating beat matched mixes with simple export to the web or iTunes.
Slackbox - Spotify playlist collaboration through Slack
humit - A social networking app for music sharing and discovery.
Join My Playlist - Listen to music live together with your friends in Spotify.
Spotify.me - Beautiful analytics on your Spotify listening habits 🎧