Jeannine Mosely has been working on building a level-3 Menger Sponge (Details at Wolfram Mathworld) for quite some time, now. My buddy Elsa Chen and I helped her drive down chunks of it to one of the OrigamiUSA conventions in New York, once.
Anyway, Jeannine has decided that she wants to finish the thing, so I was helping her out and folding some cards to use in the construction. It’s a fine thing to keep one’s fingers busy while sitting in front of the TV. That’s one box worth (500, I think) of business cards, folded into sponge-bits.