Hidden CAM in your optical mouse??

I had never tought of having an CCD camera in my optical mouse.
But now after reading this site (http://spritesmods.com/) I was suprised.
Actually the optical mouse contains two chips inside: the optical sensor and a chip for the usb/ps2-interfacing. The optical sensor is a tiny 18×18 CCD. Using this sensor we can see small images. [...]

Charlieplexing! for multiplexing LED’s

Multiplexing is the process in which several channels are combined n such a manner that they can be transmitted through a single channel.
But what’s Charlieplexing?
Charlieplexing has almost the same idea. But here it is for driving LED’s from less number of pins .
So whats the use of this technique?
You can drive a large number of [...]