AngSko's Profile

Turntable.fm is great for this purpose as well, with a great community as well. Certain rooms specifiy that songs played must be below a certain threshold of plays for the room, so you don't hear the same Teardrops On Roads Remix every hour

and I second/third/fourth Songza, it's playlists may not be the longest but if you just want to throw on some background music, its perfect.