PowerBlinken is a small and incredibly useless Mac OS X application that allows you to use your PowerBook or MacBook Pro as some sort of lightshow. It allows you to set transition, fading and blinking intervals on your PowerBook's backlit keyboard and LCD display. It requires a PowerBook or MacBook Pro to function correctly.
The backlit keyboard is controlled with the controls within the "BlinkenKey" box, while the LCD is controlled via the controls in the "BlinkenScreen". The "Synchronize" button can be checked to have both the backlit keyboard and screen blink in sync. The gray bars on each side of the window measure the light levels detected by the left and right light sensors on PowerBooks.
This program is based on Amit Singh's sample code, which I found at the following URL: http://osxbook.com/book/bonus/chapter10/light/
The source code to the program is made available under a public domain license -- you are free to do with it whatever you may please. Oh, one more thing: Please don't contact me about bugs or errors in the program -- I threw this together in the space of a couple of hours, and am not interesting in doing further work on it. That being said, I hope you derive some element of satisfaction from this little experiment.