Yeah, I use Pandora:
http://www.pandora.com/
And Last FM:
http://www.last.fm/
I like these because you can customize your station to listen to music that fits your genre. For instance, if you like Metallica, then it will not only play Metallica songs, but it will play bands that sound like Metallica too. Pretty cool stuff.
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These walls fall down around me but I will stand
And though my body be burned away I will live