I've detailed my experiences searching for a good case for my U2 iPod at The Apple Blog:

The best (and worst) case for a U2 iPod with video

If you own an iPod, you know you need to purchase and use a case in order to keep from getting it smudged and scratched. But if you own a U2 iPod, you don’t want to cover up its unique style with a case. When I purchased a 5th Generation iPod U2 Special Edition, I had a difficult time finding a case that met both of those needs, but I did end up with a great one (eventually).