Received a video iPod (G5.5) as a gift recently, and it's quickly become apparent that it requires some kind of sleeve/case. However, with a veritable, massive selection out there, which ones work particularly well, or particularly badly? I'd, ideally, like one that keeps the iPod nice and slim - something protective that doesn't add bulk, and doesn't leave marks (as I've read some sleeves/cases do). Any suggestions are greatly appreciated. Thank you!