I really love last.fm as my streaming music provider. Pandora has a special place in my heart as well, but rather than having a building of folks make some recommendations of music for me based upon some mathematical preferences, last.fm makes recommendations from other users near you. It’s occasionally wrong, but right now I can’t beat the sheer number of devices I can stream my music on. They’ve recently added X360 support through the dashboard, although you can’t stream the audio in the background of a game…Which is probably what you’re using your Xbox for in the first place. I’ve got my currently scrobbled tracks running in my sidebar widget here, feel free to take a peek. There’s some insane amount of music I’ve listened to in the past year.
But anyway, here’s the CNET article if you want to check it out: http://crave.cnet.co.uk/digitalmusic/0,39029432,49304380,00.htm