Using the API, I can automatically download a random selection of Squared Circle images, which people have kindly licensed under Creative Commons. I then slice out the biggest circle possible out of these using some functions I've written in Python, with the Python Imaging Library and NumPy. I then paste these slices together in a pile. The API also allows me to properly credit the people whose images have been used. You can see this by clicking on one of the images above.
I have been automagically generating many hundreds of these, and selecting ones I like. It's quite satisfying.