Just bought a D90 and itching to learn how to properly use this wonderful piece of equipment. I'm at the bookstore and there are several books to teach a person how to master their D90: Nikon D90 For Dummies ($29.99), David Busch's Nikon D90 ($29.99), and the Nikon D90 Digital Field Guide by J. Dennis Thomas ($19.99). Is buying one of these worth it? Or can I get most of what these books include via the manual and resources on the web? I'm also getting a free hour-long tutorial from an employee at the camera store where I bought my camera. Considering free resources (manual and online) and my in-store tutorial, do people think it is worth it to buy one of these books? And, if so, are there a line of books (...For Dummies or David Busch) that are superior to the others? Thanks!