This is a cool tidbit from TechChrunch.
People used their Twitter accounts to report whether they had experienced any snow in their area (and how much) and all of that data was collected real-time and fed into a Google Map to provide a real-time snapshot of what the snow levels were like across the Southern UK.
Great use of open technologies and counting on the masses to provide rich content (which, with enough users will outweigh any anomolies by anyone who would try to game the system).