Paul Torrens, among other interesting things, builds computer models of crowd behaviors in urban spaces. The images and video are creepy, in a cool way (at least if you're like me, and creepy in a way that you think of as sort of cool; YMMV).

Nowhere is this more relevant than at the micro-scale, on the streets, in and around our downtowns, and among the crowds of people that populate and energize the urban core. A new appreciation of urban geography is gathering steam, an urban geography of the micro-scale, where pedestrians swarm in social and anti-social networks; where innovative Information and Communications Technologies (ICT) are being deployed at street-level, digitally-enabling crowds through networked computing. Embedded in urban infrastructure and in the very products we consume, the same technology allows cities to think about—and process—the people that pulse through them.

The link above also has downloadable video of time-based simulations, PDFs of his research publications on the topic, and diagrams (showing things like chokepoints and jam formation). Torrens' main site lists other projects in modeling and analysis, including work on residential relocation, urban sprawl, and more.

[via Pruned]