Tobias Friedrich of the Max Planck Institut has used custom map tiles with the Google Maps API to display a number of large rotor-router aggregations.
Here's a little explanation of the rotor-router model (also known as 'Propp Machine'),
"Given an arbitrary graph, a random walk of a chip is a path which begins at a given starting point and chooses the next node with equal probability out of the set of its current neighbours. Random walks have been used to model a wide variety of processes in economics, physics, medicine, and mathematics."
That explanation doesn't help me much, but the maps sure are purty.