Check this out, haven't seen anyone mention this one yet:
My wife picked up her latest Warcraft time card, and this one came in a little plastic dvd case rather than a cardboard box. After our son got done dong his dance on the case, I notice the slot that holds the time card is just about the perfect size for a HuCard.
Well, sure as heck, grab the copy of Ordyne I was playing out of the duo, and pop it in, things fit perfectly into it
So, hey, if you want a case that'll hold a loose HuCard, these work great! (as long as you don't mind dvd cases next to your turbo games )