Kevin Bates has created an Arduino-powered business card called the Arduboy, which can be used for playing Tetris. You read that correctly: a business card that can play Tetris.
The business card is as thin as a few real business cards and the PCB contains a small OLED screen and micro controller. There is also a tiny speaker embedded into the business card and touch-sensitive spots to control the screen.
Bates may crowdfund the project so that more people can get their hands on this high-tech business card.