I've been carrying around a USB flash drive on my key chain to hold all that geeky stuff I need, but I decided that was totally 2006! Now that they have those SD cards that also have the USB interface I thought I could lose some of the stuff on my key chain, and just hold one of those in my wallet. The following is an example of how that could be done, as well as pretty simple instructions(I think).
Step 1: The supplies...
model SD CARD
Fake credit card
I get a few fake credit cards in things a week, so there isn't a whole lot of stress involved if/when I make a bad cut.