I noticed I was able to get fractal-like shapes in PDN. I call it "fractal-like" because I'm not sure how far down the recursion goes, and if I'm not mistaken, a true fractal must be infinitely recursive. But the image does give the impression of recursion.
and a link to the full size 800x600 pic because some of the details are lost in the resized image (warning: ~2mb pic size):
800x600 fractal_like
BTW -- Is it possible to control the amount of compression of .png's with PDN?
edit -- Updated my site with a link to the .pdn of the image. Leave a comment, mail, pm, etc. if you'd like further info on how it was done. It's pure PDN.