HP Canada has started selling printable tattoos for the Apple iPod from HP (They have been available in the US for a while now). Come up with a cool design, print it on your ink-jet printer, peel and stick it on your iPod and away you go. At any time, you can easily remove it and put on a new one.
Personally, at $19.99 CAD for 10 sheets, I can’t say that I’d be rushing out to get my hands on these. But then again, maybe you feel the need to redecorate your iPod (a la Martha Stewart) and give it a little protection from scuffs and scratches.