One of the nice things about Processing is the number of contributed libraries available.  I used the traer physics library (should be here but was down when I last checked - you can use the toxi utilities libraries instead if traer physics is not available now) to simulate masses moving under gravity towing another mass, not interacting gravitationally, on a spring.  With random positions for the start positions and velocities some nice pictures came up, all I had to do was mark the positions of the masses and springs each frame - it's that process that I used to create the graphics in the banner at the top of the page.

Pictures were interesting but I've also been able to get a 3D model as well (depending on how picky you want to be it could be argued that it represents a time history of a simulation in 3D space and so might be described as 4D..)