Everybody knows it allready, most of the shots of models we see nowadays are thouroughly Photoshopped before release.
I've seen a couple before and afters allready, but this site has alot of them - and most of the results are quite dramatic.
Pretty amazing each time what people are looking like for real

http://glennferon.com/portfolio1/index.html

beyonce-after.jpg

beyonce01_over.jpg