Pandora Internet Radio

"Find New Music, Listen to Free Web Radio" is their tagline, and it's pretty true. I really like it, as it helps to introduce new music that suits your taste, as you give input as to whether you like a song or not. It also has links to each artist/song/album to give you more info to learn about a particular artist/song/album. And after reading up on it, it also has links in case you want to purchase music from itunes or amazon.com

Pandora Internet Radio