This is a little piece of Processing art that I published on tumblr. Essentially, the program randomly generates a bunch of citrus fruit slices and uses physics-like forces to pack them into the window.

The .pde file contains the standard Processing event handlers and so on, and also handles collisions and force application. The Citrus.java contains the Citrus class which contains all of the code for drawing the actual citrus slices and updating position based on velocity.