This project uses an Arduino, a drawn keyboard using lead pencil, a paper, and a speaker.
How to make a remote-controlled origami robot with Arduino.
When paper shredder is filled by paper trash, Arduino notifies someone via Gmail that the trash bin is full and it should be taken out.
Capacitance reading keyboard for the Tyrian 2000 video game with paper and Electric Paint.
A pencil holder that also functions as a musical flashlight or lamp.