SoundCloud - Enjoy music & follow favourite artists
Subsonic - Subsonic is a free, web-based media streamer, providing ubiquitous access to your music and video.
Spotify - Map shows when two people play same song at same time
netjukebox - netjukebox is a web-based media jukebox for MPD, VideoLAN and Winamp/httpQ.
SoundClick - SoundClick is a music-based social community.
Ampache - Web ( HTTP centralized ) based audio/video streaming application