My physical therapist turned me onto a site called www.pandora.com. It describes itself as a 'music genome project.' Basically all you have to do is enter a song or artist. Let's say you enter "Come Go With Me" by the Del Vikings, Pandora will then play another song that has musical qualities similar to 'Come Go With Me.'

The process repeats again after each song is complete, as the new song will again share musical similarities with the previous, and it goes on and on. It's pretty amazing.  Each time you start over, the previous selections, or 'stations' are saved. After a bit you are asked to sign-up, but no vital info is needed, and it's free.

It's been around for a while.  Great site.

I liked it a lot.  But they blocked it where I work... We switched to www.slacker.com.  Some thing.