Firstly, a quick thanks to Steve for allowing me to post here.
Right off the bat, I'm posting a bit of sacrilege--card folding.
This is a single subunit of a Menger Sponge made from some 2008 Topps cards. It's an interesting fractal solid that you can read all about right here. The neat thing is that this type of assembly is done just with folding--no fasteners or adhesives or anything of the sort.
I didn't bother building a Sponge itself, but I did put together a bunch of subunits. Here are a couple of photos.
So now you know what to do with all your common cards, or star cards of teams you hate!
By the way, this idea came from this site, which did the same with Magic: The Gathering cards, if you're into that sort of thing.