This January during MIT's Independent Activities Period I've been working hard on my dormitory floor's music server software. We operate a rack-mount server that plays music in our showers and in our lounges. The server, dubbed "nice-rack", is a hub where all of us come together and share our tastes in music. Using the web interface we wrote, anyone can upload and play music on the server, and anyone can dequeue anyone else's music. Naturally, the server is a flashpoint for arguments about what constitutes good or even tolerable music.
Recently, the entire web interface was rewritten to use Django, and the backend was rewritten using Gstreamer. The project has reached the point in its life where we, the contributing residents of East Campus Second West, think that other people might find the code useful, so we've put the code under a BSD license and moved it to Google Code:
http://code.google.com/p/media-enclave/
Audio-enclave should be useful to anyone who wants to share a communal sound system. Personally, I have vague notions of using audio-enclave as an input to my family's living room stereo, so that we can play music from our collection on the stereo without CDs or laptops that have to be on, open, and plugged in.
Eventually, we intend to support some kind of remote API so that we can write little mobile phone apps to control the playback.