Accident statistics are a standard example for teaching count data. Some fascinating collections of data on pedestrian and bicycle accident data in New York City are available at www.crashstat.org. These include detailed maps (all intersections in New York City) as well as breakdowns by zip code. Lots of count data!
Transportation Alternatives has a press release about the maps. From a statistical standpoint, it would be interesting to study the potential effectiveness of various traffic calming ideas.