"My car was stolen today outside of 7-11 between 3 and 3:15. Black dodge truck. Did anyone see anything?" It would be community driven and targeted at locals. I imagined the draw to get people to participate would be to help "clean up" the community. Imagine a centralized resource for people to post about what they saw on 9/11 - assuming the government wouldn't shut you down.
UFO's sightings, missing pets, amber alerts could be other such usages.
Thoughts? I'm seriously considering developing this if it's well received.