There's a lot of cool things you can do with adjusting skin tones and softening wrinkles, brightening eyes and such in Photoshop - BUT I keep finding that I like most of the originals more than the "after" images. Mostly because the "after" images are too high contrast and the color is over-saturated almost to a point that hurts my eyes.

Also, I get a kick out of it when they "adjust" the model's body (See Salma Hayek's ribcage for one) into the "right" position - even though the anatomy was right in the original! :D