The images below are drawn programmatically. I wrote a drawing framework called Giotto which makes use of the Processing.org Java library.  These images are comprised entirely of geometric shapes, drawn ad infinitum by the machine.  You may recognize circles and lines.  There's also a powerful sine wave manipulation framework here that I've been writing and re-writing for a few years.  Even the color palettes are constructed from wave interference.
Each display technique, the trees, the clouds, the strange bursts of light, are Drawables, Java classes that can be plugged into the Giotto framework.  In the future I'd like to have Giotto support Groovy Drawables to better integrate the coding and drawing experience.  How nice.