I used to be a big fan of the Magic Lantern Guides until I started buying Peahcpit. They do the best, in my opinion. This is not out yet, but I saw the entire book before it pubbed courtesy of a friend of mine. I have to say I love the approach to covering the 50D. Not only does it cover the mechanics of using the camera, but also the technique and why. There is a sample chapter on line here. (click the sample content tab) I bought my advance copy at barnesandnoble.com, but I am sure Amazon or any other place will stock it too.