I know there are people that have lots of cookbooks (read eGullet sometime, there are numbers in the 6 figures). But how many of those have you actually cooked from? Do you try to cook your way through a new book you buy, or just flip through it for inspiration?
I have about 10 recipe books myself, plus a Cook's Illustrated magazine collection. My biggest success has been Bittman's How to Cook Everything Vegetarian, but I'm sure I've only made 1% of it by recipe count.
I have sort of a latent fantasy to cook every recipe in every one of my books, but I know it's hopeless. That's the kind of thing people make movies about, apparently.