I stumbled across a reference to an interesting music site called Pandora. It's basically an online radio station, but it is totally customizable and adaptable. You tell it a song or artist you like, and it will then start playing songs that share similarities to what you said you like. It s based on something called the Music Genome Project. Songs are analyzed based on a bunch of different qualities (rhythm, harmony, vocals, etc.) so they can be categorized. While the music is being played, you can also give feedback to say whether you like the song or not, and even get an explanation of why that song was selected.
I was pleasantly surprised at how accurate the music choices were. I entered "Peter Gabriel" to see what songs it would play, and the very first song it chose is one of my favorite songs by the "Talking Heads" (This must be the Place (Naive Melody)). I had never before made a connection between the two artists. I knew I liked them both, but didn't really think they were that similar. I'll have to give it some more time and see if Pandora continues to provide a good sampling of music for me. But so far, I'm impressed.
Oh, and Pandora is totally free. So give a try!