Roger Alsing recently wrote an evolutionary algorithm that recreated the Mona Lisa out of only 50 semi transparent polygons. The results are an impressive testimony to the power of such an approach (the final image being the 904,314th generation):

Mona Lisa evolution

From his post:

This weekend I decided to play around a bit with genetic programming and put evolution to the test, the test of fine art 🙂

I created a small program that keeps a string of DNA for polygon rendering.
The procedure of the program is quite simple:

0) Setup a random DNA string (application start)

1) Copy the current DNA sequence and mutate it slightly
2) Use the new DNA to render polygons onto a canvas
3) Compare the canvas to the source image
4) If the new painting looks more like the source image than the previous painting did, then overwrite the current DNA with the new DNA
5) repeat from 1