Aristid Lindenmayer, the biologist, has developped a very simple language with only a few symbols to construct structures of plants, classical and new fractals. My program Lindenmayer takes simple L-System terms and the result is a fractal graph like the example below.
You may download the Lindenmayer program (english version, 571 kB, november 2003) for personal use. There are more offers in the German version for those, who are able to understand the German language. You can also try out my interactive java version on the page Lindenmayer II.
More hints: Read the essay Wachstumssimulationen by P. Jossen and Daniel Eyer (Switzerland) written in German. Watch the section Branches for computer generated twigs.