One of the session's I've attended was by Adrian Holovarty on Screen Scraping. Adrian (of Django fame) made chicago crime to help the citizens of Chicago. Citizen ICAM, police department site that has a database of crimes but is not user friendly for browsing. Has a pretty bad interface only allows 14 days of searching. Embedded at the bottom is "tabular" report, which actually has useful information. Wrote a screen scraper which looks at the latest 90 days, in two week segements. The search radius only allows one mile search radius. Edited the form and changed the radius to 90 miles (and it worked!). Used the live http headers firefox plugin to follow http stream. Adrian pulled all the data from the 90 mile radius. Then next step was to geo code (long/lat). Yahoo maps provides a good geocoding api.
There is also a route finder, which shows crimes along a user entered route. Using postgis, it allows one to do fuzzy searching for GIS. This allows one to do searches like "see crimes within 2, 4, 8 blocks". It also lets you find your police district or ward. Another journal publishes a police blotter. The police blotter doesn't publish the case number (primary key), so he tries to deduct the case number against the crime database by searching for addresses (by hand). (Yahoo term extractor doesn't find it). Can't post the link to this right now. Chicago PD also has a most wanted list that links photos with case numbers. In the future this will be linked in to show the perpetrators mug shot. A side benefit was that Adrian got to meet with the cops. They called him the day chicago crimes was launched.