I just ran across a web site that blew my mind called Scribd. It's the world's largest document sharing network and it's free to register. You can search and download millions of PDF documents that other people have uploaded. There are documents on every topic you can imagine and I found a ton of interesting music docs.
This is what the Internet was really supposed to be about- the world's libraries at your fingertips. Scribd is simply incredible, I wish I had known about this before now.