Wired has a round-up of the latest forays into designing an electronic pen. The newer devices use various technologies to translate movements into digital ink. One uses infrared and ultrasonic signals, another a tiny digital camera on proprietary paper with teeny tiny dots, and here’s the coolest sounding one which employs a laser: “The sensor in the VPen measures motion in three dimensions using a technique based on the Doppler effect, the phenomenon created by the shift in the wavelength of light from a moving object. The VPen can write on any surface that reflects light, from paper or cloth to computer screens or even skin.”