Google’s Open Spot Android app lets people leaving parking spots share the information with others searching for parking nearby. Running the app shows you parking spots within a 1.5km. New parking spots are assumed to be gone after 20 minutes and removed from the system.

People who announce open spots gain karma points, while those who report false spots, known as griefers, are on notice:

“We’re watching for behavior that looks like a griefer spoofing parking spots. We have a couple of mechanisms available to make sure someone can’t leave a bunch of fake parking spots. If we see this happening we will take steps to fix it.

This is a simple example of a context-aware mobile app that can further benefit from also knowing that you are driving, as opposed to riding, in your car and likely to want to find a parking spot, as opposed to doing 70mph on I-95 as it goes through Baltimore.