These “WaSaBi” cases from Gametech will dress up your handheld system and add some protection as well. They’ll cost you $27 and they are available now. You have six versions to choose from for your DSi, DS, or PSP.
It beats a plain old one color DSi and yours will look unique. Until someone steals it from you because they also think it looks nice. But until then, by all means enjoy it.