The second place winner at Mashup Camp was ChicagoCrime.org. Created by Adrian Holovaty, ChicagoCrime mashes data from the Chicago Police Department's Citizen ICAM database of reported crime with the Google Maps API to show you where crimes of different types have recently occured in the Chicago area.
A useful tool for somebody looking to rent or own in Chi-town. Yes, it has hook-ups and parking, but what's the violent crime rate like in the neighborhood? Search by ZIP code, ward, police district, or type of crime (among other parameters). Map it up, zoom in to see the addresses, and click on crime events to read the grizzly details.