Uplister was a playlist sharing community with several hundred thousand users that operated from 2000-2002. The service allowed music fans from all over the world to create and share annotated playlists of their favorite music and discover new music based on shared personal tastes. Here's an example playlist, and another one, and the former home page, and some cycling images of Uplister running inside Winamp.
Here are more screen shots, including some of Uplister 2.0, from Matt Glass, Uplister's UI designer.
Check out this excellent paper on Uplister called The Playlist is the Thing by Jennifer Waits.
What some former Uplisterites are up to:
Mike Cating: Cating Systems
Dan McGarry: www.danmcgarry.com
Gordon Murtaugh: Email him
Lisa Rodriguez: Porter Novelli
Toni Schneider: Automattic
Ann Sera: Codebright
Jeremy Silver: Sibelius
Catherine Smith: foolsFURY
Mike Taylor: Microsoft
Jennifer Waits: SpinningIndie