Another fun example of a computer generating mezmerizingly complex art from simple code is that as a kid, I wrote a Langton's Ant implementation in QBASIC on a DOS machine (don't remember the version). IIRC this was using Graphics Mode 1 (320 x 200 pixel framebuffer), and I used PSET and PRESET to draw white and black pixels. This so far sounds ordinary but: The cool thing was that I forgot to write the bounds check…
http://chengsun.github.com/walk.html
I still am a "kid", and it amuses me that I'm making the same stuff on modern platforms that have already been done on DOS machines by kids like me.