I found an interesting article on the new services like Pandora and Last.fm that try and predict songs you will like, and similar ones that go on your hard drive. Best point?
you should get “an ongoing music experience,” that sticks the right gaps or overlaps between songs, never separates Led Zeppelin’s “Heartbreaker” from “Living Loving Maid (She’s Just a Woman)”, and appreciates how to bring the party up and then slow it down.
No shuffle’s figured out that danged Zep thing yet.