I’ve been using Gelaskins for a couple of years now to customize my various devices. As a photographer I’m always looking for ways to display my work. Put the two together and now my “Creative Portfolio” is on my MacBook Pro, iPad and iPhone.
P.S. I love it when the TSA agents are so busy looking at my photos that they forget to make me take off my belt! 
Check out Gelaskins here. You can buy existing designs or upload your own!