Enough of the creator shelves for a while, how about we move on to "Art instruction and comics careers"
Here's one where I AM going to go with the "obvious" pick. There are some terrific books on "how to draw" or even "how to approach a comics page" -- Burne Hogarth's DYNAMIC... (ANATOMY, WRINKLES & DRAPERY, FIGURE DRAWING, etc etc) series, Will Eisner's COMICS & SEQUENTIAL ART or GRAPHIC STORYTELLING, and so on, but there's one book that I think that each and every comics reader in the world, whether or not they have the SLIGHTEST interest in ever drawing a single comic ever, really should have on their bookshelf:
UNDERSTANDING COMICS by Scott McCloud.
McCloud's book is just as great for the casual comics reader as it is for any creator, laying out a tremendous amount of practical theory about comics layout, storytelling, nomenclature, style, and so on.
I don't know if I agree with each and every theory that McCloud posits (and, really, I'm not even sure that Scott agrees with it all any longer), but there's enough "Oh fuck, I never thought of it THAT way" in there that will probably blow your mind.
What's great about UNDERSTANDING COMICS is that it IS comics, and it is eminently readable AS a comic as well.
Regardless of this feature, I'd place UNDERSTANDING COMICS as one of the MUST HAVE books in your collection! Go go buy it now!