Pyro - Spotify music voting for parties
Brain.fm - Music designed for the brain to enhance focus, relaxation, meditation, naps and sleep within 10 - 15 minutes of use.
Playlistful - Collaborative playlists for parties!
Slackbox - Spotify playlist collaboration through Slack
klaep - music collaboration - klaep is a social music collaboration network for musicians
Radionewify - Only music you've never listened to before