Playlistful - Collaborative playlists for parties!
Jukebox - Collaborative music player
Festify - Festify is a free Spotify-powered app that lets your guests choose which music should be played...
MisterJack - Make and share playlists
Join My Playlist - Listen to music live together with your friends in Spotify.
klaep - music collaboration - klaep is a social music collaboration network for musicians