I went to a town hall type deal with Tim Westergren, founder of Pandora. It was very interesting listening to him talk about how the Music Genome Project came out of working as a film composer, and finding that the biggest part of that was figuring out what kind of music the director liked. So the Music Genome Project was hatched to break down the components of songs and match up songs with similar characteristics.
I first heard about it from a list member who had set up a station and rated some songs and then looked at what it told her were the common elements. I have a few stations set up, but tend to listen in Quickmix, which bunches all my stations together.
Pandora gives me the chance to start with the stuff I already know I like, and expand out from there. In my car, I tend to listen to news radio, but at work, I found it had to be really loud for me to follow. Plus as I would get into a groove, I would lose what they were talking about. So music is a better background for me, but regular radio was sometimes fuzzy and filled with commercials and DJs. (Some of the DJs are lovely.) So, Pandora worked great. It was also a great solution for someone who appreciates world music, pop, country and musicals.
Also, you can skip stuff, scroll back to find out what that great song was, and so on. And, as Tim pointed out, their catalog is huge compared to what even the most eclectic station tends to play.
Now, I just need a new phone so I can carry it with me.