Are you looking for Bit Torrents? Well, let's first figure out what the heck they are. From Net For Beginners Guide Paul Gil, I found a BitTorrents 101 handbook that successfully explains what they are and how they work. From Paul:

"BitTorrent networking is the latest form of Internet P2P (peer-to-peer) file sharing. BitTorrent works by simultaneously downloading small bits of files from many web sources. BitTorrent downloading is extremely easy to use, and is completely non-profit and free of user subscription fees."

So, that taken care of, I found a search engine that helps you find these things, and it's called bitoogle.com, the "torrent file search engine." It's pretty bare bones but I plugged in the term "music" (I know, how imaginative of me) and got back a ton of results.

Related: Find more music on the Web with these audio and video resources.