I recently discovered last.fm, an online “radio” sort of thing where you can basically tag music you like and create your own “radio station” and listen to music you like non stop in 128kbps, no commercials, no interruptions or you can tune in into live radio stations that match your tags. So far I must say it is fantastic.
It also offers a lot of user interaction features, including e.g. a recent tracks list:
Let the music play!