Not sure if it came up earlier in this thread, but be sure to check out Pandora Free Internet Radio .

You enter a song/album/artist that you like and it plays only songs that it believes are similar based on a database of hundreds of attributes that are assigned to each song. It's pretty amazing how well it works. I've discovered a lot of new music from it and find myself buying a lot of it after hearing it for the first time on Pandora.

Epic 80-800: HG Cherry