Heartbeat - Listen to music with your friends together, on Spotify
Liyo - Stream your favorite music live with friends 🎶
haminet.fm - Listen to music with your friends while working
Parallel - Listen to music with friends over Spotify at the same time
Vertigo - Vertigo is a web and Android application that allow you to listen to music with friends in real-time.
Partyhero - Pass your friends the aux!