I just finished this book last weekend. Anyone else read it? It's from the guy who runs smartfooball.com, and I would highly recommend it. It's somewhat short, but it helped me understand some stuff I never really knew. He goes into detail about the stuff like match-zone coverages we use, and discusses the "get open" WR routes Beck installed (it's from the run-n-shoot). I've also spent quite a bit of time at his website over the summer, and it's a really cool site if you're into X's and O's.
Website is here: www.smartfootball.com
Book is here.