This answer almost deserves its own announcement thread, but Google are currently Beta'ing a new portal called Google print. They are scanning ALL books, with obvious attention paid to copyrights.
http://print.google.com
Searching for C# I got this result.
http://print.google.com/print?q=C%23&btnG=Search+Print
Pick which one you like and read all the pages online.
It's very quick.
You will need a gmail or other google account to read the books.