Google Open Spot

Open Spot, launched by Google, allows all Android (2.0 and up) users to search for unclaimed spaces marked by Open Spot users, as well as mark their own should they leave a spot. While initiatives such as this have been tried before, this is the first one that is backed by such a large user base. Once spots are marked, they are color coded based on how long ago they were marked. While the app is free, it does not come with features such as notes, which would allow users to mark a spot as metered, free, or permit parking. The success of such an app depends entirely on user usage, so if you are a frequent city driver make it a habit to mark your parking spot when you leave. You never know, this app could save you an hour of driving in circles looking for a spot one day!