Slackbox - Spotify playlist collaboration through Slack
MusicTwin Finder - Find your MusicTwin by your Spotify playlists in 5 seconds.
Playlist Machinery - Tools that help you create & organize your Spotify playlists
Symphona App - Designed to make orchestral staff management a breeze.
PlaylistMap - Connect with Spotify playlist curators from around the world
JamBuddy - Find and collaborate with musicians around you thru Spotify