My son found this deal on fatwallet. "Tony Northrup's DSLR Book: How to Create Stunning Digital Photography" Today only.
I don't know anything about the book or the author, but for free there's no harm in checking it out. I downloaded it to my Xoom tablet. There are many color photos in the book so I'm not sure how practical it would be on a non-color (original kindle) tablet. Here is the link: