I actually was telling fellow ADDer Anna about this site and thought others might think it was as cool as I do! It's completely free with very minimal advertising mess on it.
So if you listen to music a lot, try it! I love it and can't believe it isn't more well known.
The link is WWW.PANDORA.COM
Hard to explain what it is, may be easier just to go look at the site instead of reading my rambles trying to explain it. Basically it creates and tailors "radio stations" to whatever music you like. You enter an artist name or a song title and it builds a radio station for you with those similar traits. Then as you listen, you rate the songs good or bad if you want and that process narrows the songs Pandora picks to what you really like. Like a said, you will probably just have to try it out to really understand it. \It really is cool because you hear music from groups that you have never heard of necessarily but is the kind of music you like! When I come across really cool stuff like this, I like to spread the love. I am very passionate about music so this was the coolest thing ever for me to use! Let me know what you think! -Siren