I'm a big fan of DIY and the whole "Maker" movement that has been picking up speed recently. One of the godmothers of the movement is Limor Fried, who runs the excellent parts and project web site called Adafruit Industries, and she has whipped up what is probably the coolest business card ever designed.
Remember the old Spirograph toy? Loved that thing as a kid. This business card disassembles into one and can destroy a whole day's productivity at the office. I'd love to get my hands on one.