A clever way to multiply numbers.
Easy Graphical Multiplication Trick - The funniest videos are a click away
How many words can you write on your calculator?
Calculator Word Challenge - Watch a funny movie here
How to play tetris on a simple Canon calculator? Just enter 153349 and hit + and - at the same time. Neat trick, isn't it?
Play Tetris On Calculators! - video powered by Metacafe
Turn a TI Graphing Calculator into an Intervalometer and Create Time Lapse Videos
Take a look at this heavilly modified TI-83+. It even has a real PS2 mouse and keyboard attached!
How to turn a calculator and an am-radio into a metal detector

Fun with calculators
Have a look at some funny videos I found...