BeatSense - Discover great music hand-picked by real people, in a single click. FREE and in real-time!
Openwhyd - Collect and Share the tracks you love.
Twinjack - Stream Spotify music with anyone with just a link
Quorus - A new way to listen to music through collaboration
Spotify_cmd - Spotify_cmd is a tool to control a running instance of Spotify under wine.
üWave - üWave is a self-hosted collaborative listening platform.