And now for something completely different by Instructables member TannyPB - an Arduino-powered Kaleidoscope. Based on a toy that was popular in prevous centuries, the Kaleiduino instead blinks a group of LEDs in various colours, whose reflections are enhanced using a group of mirrors inside a home-made tube.
The neat thing about making an electronic version is that you can update the patterns yourself, or perhaps add an accelerometer to make the display more interactive. Or if you're not interested in the final product, the instructions demonstrate how to multiplex LEDs to get more control with less GPIO
If you're looking to make your own colourful LED-based project, consider our Freetronics RGBLED: full colour module. It includes a bright RGB LED on the top of the board and a WS2801 constant-current, addressable, multi-channel LED driver on the back. This smart module can be daisy-chained, so you can connect a number of these together in a string and drive each of the module colours individually from your microcontroller. For more information and to order, visit the product page.