Actually, I was looking at a project where someone took a Linksys router, put OpenWRT on it, added a USB sound card and used it to receive streaming audio. I was thinking of doing something similar. He used an LCD display to show the track info, but for me, I don’t think I’d need that.
At this point, what I’m considering, is using a few dumb clients like that with a server that would stream one thing to all and using a PDA to control the stream to them.