Quick plug. Sharing the groove. This site + BitTorrent = live, concert-recorded bliss. They've got hundreds of high-quality concert recordings. I'm d/ling Sigur Rós live in NYC, 2002.
Err, it's for research purposes. One must wonder what, if anything, ASCAP has to say about this. Many of these bands have explicitly pro-taping policies, but not all. And the site has a strict bar on commercial recordings. So this seems closest to the "free downloading = free advertising" model.