I know this is rather an old script but I really like using the l-system generator and have done a sort of tutorial that really is just a bunch of images in which I have tried to illustrate the various settings. I would have liked something like this when I first started using the script and refer to it occasionally still.
Zaug
Oh yeah, the address… :o
www.zaug.netmegs.com/l.html
Let me know what you think.