TI 59

I actually owned of of those when I was in High School. I programmed a series of magnetic cards with all of the formulas I would need on my Physics final exam. During the test, the room was quiet except for the occasional whir of the motor pulling the card through the reader. The instructor naturally came to investigate. He told me that I couldn't use it on the test. I pleaded my case that he said "we were allowed to use calculators" and he relented. Naturally, I aced the test. :)

haha, until AP we were allowed any calculators, so I used a TI-83+ with formulas just typed in and saved to remind me. It made stuff easy :)