I collect NES cartridges. I've got a pretty sizeable collection too. Thing is, I only collect the games that I'd consider playing at some point. That means you'll never find crap like Sesame Street 1-2-3 or Bible Adventures in my collection. Right now, I believe I'm at approximately 215 titles in my possession. I scour E-bay and second-hand shops periodically for anything that might interest me, but those titles are becoming fewer and fewer.
Here's all my games, conveniently stacked together:
Some of my high-end games. These ones tend to be quite rare.
I've got a lot of complete sets too, like Mega Man, Ninja Gaiden, Contra, Dragon Warrior, Lolo, Adventure Island, T.M.N.T. and so on. I've only been collecting for four years, so my collection's pretty impressive for such a short span.
Jam it back in, in the dark.