JukeJam

From Mark Judge:

JukeJam is primarily a juke box for multiple users over a network, but is also useful for any situation where you have a collection of MP3s on your computer and you want to be able to request a play list. It's perfect for in the office, or at parties! You can request and comment on tracks, and there is also a chat system, allowing you to chat to other JukeJam users. The system has a server on one computer with access to everyones MP3 collection, and as long as each user has access to that computer they can request tracks to be played. There is the option to play the MP3s from the server computer (over speakers) or, on each of the user's computers separately (over headphones).