From Sindre Mehus:
Subsonic for Debian/Ubuntu share your music with friends, or to listen to your own music while at work. You can stream to multiple players simultaneously, for instance to one player in your kitchen and another in your living room. It is designed to handle very large music collections (many thousand albums). By using transcoder plug-ins, Subsonic supports on-the-fly conversion and streaming of virtually any audio format, including FLAC, APE, WMA, Musepack, WavPack, Shorten, and OptimFROG.