I'm adding this after experimenting with muxtape.com and skreemR web sites...
I showed them to my daughter and she showed my the pandora.com web site.
Its kinda cool...input an artist you like and it will create a "radio" station that will play that artist and artists like that one.
You can create many different "radio" stations and they are saved in your account (free).
Also supposedly as you listen to songs you can give them a thumbs up or down and it will factor that into your web site.
There is some extras..that show you additional information...
Anyways...I thought it was neat.