Momixa - Pick two songs and get the perfect mix
Join My Playlist - Listen to music live together with your friends in Spotify.
Pacemaker - Create and share mixtapes with friends
Parallel - Listen to music with friends over Spotify at the same time
FIEND.fm - "Hot or Not" for music discovery: 2 hrs of tracks in 2 mins
TuneMeet - Chat with people who are listening to the same song