My mate Philipp Lenssen came up with this interesting experiment which he called "
Ajax Pixel Group"
Basically you click on a pixel to revert it's colour so you can make some interesting images.
Why is this such a big thing?
Well, it's because it's all done in real-time, you'll see the page change before your eyes while you're making your picture.
In fact, he's even made a video of it:
http://blog.outer-court.com/videos/pixelgroup.wmv
(My claim to fame is making the smiley face and Google logo at 14:45 in the video

)