musiqpad - Musiqpad is a social-music software platform for users to host their own ‘pads’ (rooms).
Plexamp - A small music player with a number of unique features
Twinjack - Stream Spotify music with anyone with just a link
Vinyls - Vinyls is a music player that lets you listen to your music without any complicated setup.
üWave - üWave is a self-hosted collaborative listening platform.
Poolside FM for iPhone - A pool party in your pocket