Mine aren't, but they do run mostly in one direction: what the music industry pigeonholes as "classic rock", with a definite leaning toward Southern rock. My iTunes library has a bunch of good stuff in it, but I decided to give it a try. I set up a station, called rather predictably Tron Guy Radio, and primed it with the stuff I like from my library.
Two of the first three songs it played at me are from artists I never heard of, but liked when I heard them; the third was a song I knew I liked. I think I'll keep this one.