Check out Lou Romano's blog for a great in-depth look at the development & production work he did for the recent Pixar hit film, Up.
http://louromano.blogspot.com/2009/05/art-of-up_3697.html
The great illustrator/ art director shares many images he created to inspire the look of the final film. But beware, if you haven't seen the awesome movie yet, the post does contain spoilers (of sorts).