Have you heard of this? My son David turned me on to it today. It's a free music-listening site where you can enter your favorite artists and listen to continuous songs by that artist as well as by others you may not have ever heard of but who resemble that artist.
So it's a great way to learn about other artists and listen to free music. You can't download songs, but for just listening it's great. It's also fun to set up new music "stations" and see what songs are out there in the musical universe.