Heard this on the C|Net Buzz Out Loud podcast just now, that GrooveShark.com wants to use P2P technology for legal music sharing, downloading, and purchasing. Interesting hybrid concept. And if you mention you heard about it on a C|Net podcast, you will get your beta account request approved. So give it a try and let me know what you think.

By the way, if you don't already, give the Buzz Out Loud podcast a listen. It's very ... energetic.