By far the best point-light walker demonstration I've seen is at biomotiolab.ca. I'm classifying this as an illusion (see post label) because, of course, point-light walkers aren't really walking people -- they are just a few white dots moving around the screen. Comparing the male and female versions is particularly fun if you've ever wondered what exactly it is that makes for a stereotypical male or female stride.
It also appears that there is an experiment you can participate in if you want to help with this kind of research.
