Parallel - Listen to music with friends over Spotify at the same time
BeatSense - Discover great music hand-picked by real people, in a single click. FREE and in real-time!
Slackbox - Spotify playlist collaboration through Slack
üWave - üWave is a self-hosted collaborative listening platform.
Join My Playlist - Listen to music live together with your friends in Spotify.
musiqpad - Musiqpad is a social-music software platform for users to host their own ‘pads’ (rooms).