1. MandleBrain.
This is a Mandelbrot set generator program written by Evangelista Danny Brewer <danny@cjnetworks.com> that is free and may be freely distributed.
It is FAST on a PowerMac,and does color table animation, which is sure to be a hit with kids.
It may be downloaded from Danny's homepage at:
http://www.cjnetworks.com/~danny/MandelBrain/MandelBrain.html