The Google book scanning project is a massive project to register and present online excerpts from the World’s stock of books. This means that also jazz guitar books are or will be part of books.google.com Here is, for example, Tommy Tedesco’s For Guitar Player’s Only, with numerous nifty little nuggets for those who want to make it in studios. Most of the book seems available. And here is Joe Diorio’s Jazz Blues Styles. Finally, one I look forward to studying: Mitch Holder’s The Jazz Guitar Stylings of Howard Roberts.