The book - one of the most sought after in the series - is no longer published (UPDATE - As of July 2012, the book is now being republished and can be purchased using the link at the bottom of this post).
Originally published in 2001, this book (144 pages) is filled with amazing works of art by many, many artists who helped shaped the film, but I couldn't help but see (and feel) the strong influence from Harley Jessup (Production Designer) in this book. His marker and ink work is stunning and so filled with detail yet feels so easy at the same time. Even his acrylic work (which donned the cover) is beautiful and filled with so much life.
Although the book is true to its name and is filled with mounds of art - there are also great insights written and unwritten that you can pull from the pages. For instance, Pete Docter (Director) noted that "Sullivan's design evolved over two years of development and thirty different 3-D sculpts." He also noted that Mike's design basically remained the same from one of the original sketches.
Some of the unwritten observations that you can pull from the book are related to the environment and the character Boo. In the early concept drawings, the monster world looked very ominous and contained a lot of images of leafless trees and shadows - I'm glad that they ended with a more "city feel" so the audience could relate on a more personal level. The other thing I noted while browsing the pages was that the character Boo was supposed to originally have red hair. This wasn't stated in the book but after countless drawings showing Boo with red-orange hair, you can only assume this was the original intent.
Finally, an interesting point that Docter noted was that the "monster world" has no comparison to our world, so he told the original concept artists the idea of the film and then let them roam freely in their imaginations to develop the monsters and their world. It's this freedom to explore and create that draws (pun intended) people into Pixar and allows the artists to create such beautiful work.
Pixar Post - T.J.