Heartbeat - Listen to music with your friends together, on Spotify
Parallel - Listen to music with friends over Spotify at the same time
Festify - Festify is a free Spotify-powered app that lets your guests choose which music should be played...
Slackbox - Spotify playlist collaboration through Slack
BeatSense - Discover great music hand-picked by real people, in a single click. FREE and in real-time!
Join My Playlist - Listen to music live together with your friends in Spotify.