Just "discovered" www.pandora.com. You join up, name your station, type in your band(s); i.e., Rolling Stones, Jimmy Buffett, Tom Petty, Beatles, Janis Joplin, are on mine. From there it intuits what kind of music you want to listen to and I've been treated to the Doors, CCR, Bob Marley, etc. So far, only one maybe 30 second commercial. You can ban a hated song or buy a loved one and have more than one station for different genres.
I love Pandora! So much so that I subscribed not too long ago. Highly recommended.
I've been hooked on Pandora for some time. The thumbs up and down really work, and you can add variety to your station by inputting multiple bands.
What I really like is the amount of information provided. It keeps introducing me to more music when I start with an obscure band.
Just signed up a few days ago.
Now that I have an iPhone, I can listen almost wherever I'm at.