Some would say that an electronic dice would take the fun away from the game, but I’m not sure that’s always true. Anyway as the friends from PyroElectro say “we’ll make it anyway”. It’s based on the ATmega8 which controlls 7 LE’s that show you the number. All the schematics and source code is available for download.
The muscle powered Dice is based on Faraday’s law, consisting of a tube with cylindrical magnets. The tube is wound with a coil of magnet wire. As the tube is shaken, the magnets traverse the length of the tube back and forth, thus changing the magnetic flux through the coil and the coil therefore produces an AC voltage which is used to drive the electronic dice. Pretty simple now that you know how it’s done 
Electronic Batteryless Dice: [Link]
Keith published a new article regarding a rotary encoder, the little potentioemeters that can spin forever. The article is about a Led calculator that he planed building for a while, and since the circuit has a rotary encoder he gives you some info about rotary encoders.
Led Calculator With Rotary Encoder: [Link]
This circuit provides a constant amount of power to the LEDs and also provides a constant amount of light for a longer period of time. This circuit also allows the LEDs to run on almost any normal voltage above 4 volts. This means you can use multiple sources of power for the same light, a few AAA batteries, or even a car battery.
Constant Current Supply For LED’s: [Link]
The project uses (2) 5×7 LED Displays, so 10 columns and 7 rows for a total of 70 LEDs. The matrix works on the basis of scanning the display very quickly. The 4017 chip is used to switch between the columns. The way the 4017 chip works, is that when a signal is sent to a certain pin, 1 of 10 of the other pins is sequentially activated. The way the software works, is it tells the chip to switch columns, which sets one column high.
The software then makes the parallel port turn on the individual LEDs in that column needed. This is done very quickly, many times a second. It’s a fairly easy concept and it turned out the programming was easier than the author had initially anticipated.
And the great thing about this project is that it also comes with a font writer, which is basically a software written also by the author of the circuit to help him quickly design animations.
Computer Controlled LED Matrix: [Link]