The other day I was wandering in the library when I bumped into the book Urban Modelling: Algorithms, Calibrations, Predictions, published by M. Batty back in 1976 (!). Since then, he and his team at CASA have made many contributions to the field of urban studies with new modelling developments and applications.
Some of the softwares developed at CASA (including GMap Creator) are available for download here. You can play with your own Von Thunen Model!
[Image Credit: CASA]