An internet community forum solved a crime of car theft within 48 hours, as per the story "An auto dealer in Calgary lends a car for a test drive — a 1991 Nissan Skyline GT-R. The test driver and another person don't return the car".
The dealer files a police report and also posts a message in beyond.ca (forums.beyond.ca/st/212943/1991-skyline-gt-r-stolen-calgary-ab-cash-rewardpics-of-criminals-inside/) forum, as well the dealer used Facebook/Google Maps to pinpoint the thief's location. Interesting.
Full Story: nytimes.com/2008/04/13/automobiles/13STEAL.html?hp=&pagewanted=print