Elvis Costello once remarked, "Writing about music is like dancing about architecture." In my opinion, books about comics - with the exception of Kavalier and Clay - often miss the point; they too often focus so much on the academic/structure that they avoid the whole point of comics. The turning point came with Understanding Comics, where Scott McCloud self-referentially used graphic literature as a way to deconstruct it.
It isn't so amazing, then, that Dennis O'Neil has written The DC Comics Guide to Writing Comics, less a meditation on the art of comics than an exploration of structure, and a book which (probably) should have come out in the late 1980s. It is a very basic how-to guide, and does not go into some of the more artistic aspects. This is to Alan Moore's (rumored upcoming) comic writing guide what Lester Dent's pulp outline is to Raymond Chandler's The Simple Art of Murder...but we all have to start somewhere, and this book is one of those "if you love comics, you gotta have it on your bookshelf."
Next, deconstructing comics further is The Science of Superheroes, which attempts to provide scientific explanations behind some of the more common heroes. Basically, Marvel's heroes are based on dubious science (surprise, surprise), and DCs come out slightly stronger. Surprisingly, the authors provide great theories behind the powers of Green Lantern and Aquaman, which will make some Aquaman fans very happy. It's in a very easy-to-read format - well worth checking out of your local library. (And consider this a plug for the St. Louis Public Library system - second, in my opinion, only to Chicago's library system)
Finally, thanks to my employer's Christmas party, I was given a copy of How to Be a Superhero as a gift. It knowingly embraces every super hero cliche and simultaneously celebrates and tweaks them. It's definitely a humor book, and unless you're the kind of sad individual tweaked in either Fanboy Rampage or Post-Crisis, worth reading (although, again, probably more worth checking out of your local library).