
Oxidizer
"Oxidizer is a free open source fractal flame editor for the Apple Macintosh, running OSX 10.4 or greater." Although not quite the same as chaoscope (it is a fractal flame generator instead of a strange attractor generator), it is a great alternative to chaoscope. The program takes a little getting used to, but there are several very useful tutorials on the web. Once learned, it is a very powerful application.