Randomly stumbled upon this website.  Really cool site featuring a portfolio of photos that Greg Apodaca has Photoshopped, with rollovers so you can see the before and after images.  What’s really neat is that he shows upclose views of his ‘shops, and also explains how he altered the originals. This would make a great resource if you’re looking for some examples for your own project.

http://homepage.mac.com/gapodaca/digital/blonde/blonde1.html