I heard that google was scanning lots of PD books but I can't seem to find any good music books.
There are many great music method books that were first published in the 1800's and are still being published today. Wouldn't these also be public domain so that Google could scan them?

I was looking for the Samandi Bass Method and and found this site
http://www.filestube.com/s/simandl
I've never used a file sharing site because I thought they generally dealt with illegal file sharing.