The guys at UNC have been busy with crowd simulation recently. Here's a couple of recent papers.
Aggregate Dynamics for Dense Crowd Simulation
This paper described method which is similar to boids, but instead of the boinds rules of cohesion and alignment, they use incompressible fluid simulation. Scales well to thousands of agents.
Directing Crowd Simulations using Navigation Fields
Directing crowd movement using mixture of RVOs and potential fields. I can imagine this method could be easily help certain scenarios appearing in games, although it might be too expensive. It provides some interesting ideas none the less.