Spotalike - Spotify playlist with similar songs, according to Last.fm
Heartbeat - Listen to music with your friends together, on Spotify
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
Liyo - Stream your favorite music live with friends 🎶
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
Parallel - Listen to music with friends over Spotify at the same time