I know, it's a dumb question, but might turn out to be interesting what the people around here ACTUALLY HAVE ON their key-chain. I'm talking about interesting, nerdy, custom or just funny stuff that you guys use to keep your house keys on.
OK, I'll go first:
I've got two actual, real-life Xilinx Virtex FPGAs, glued back to back. They kinda look nerdy... to me at least. I made this when I used to work for a company, a few years back. They were found to have a few faulty pins and were replaced with other working chips. These were tossed away.
Seemed like a shame really, so I took them and turned them into what could be a potentially expensive keychain. I searched for similar part numbers on digikey a few years ago and and these puppies went for quite some cash.
And yes, they look beat up, but that again, they've been in pockets, bags, had sweat on them, so it's to be expected they'd loose their shine along the years.
So, show us what nice stuff you have