tried before, but given that things like this need a critical mass of followers to be effective, we're particularly jazzed about Google's own initiative. Dubbed 'Open Spot,' this bloody brilliant Android (2.0 and up) application enables motorists to search for unclaimed spaces that have been reported by other Open Spot users, and once they head elsewhere, it allows them to mark their spot as open and available. Once a spot is marked, the color gradually fades from red to yellow the longer it remains unclaimed. We've given it a quick test here on our end, and while it seems snappy enough (and yes, we definitely received a Karma Point for every space we dropped), the obvious omission is the ability to add notes to each marked place. There really should be a way to denote whether a spot is metered, covered by some wacky city permit law or submerged in a foot of water -- here's hoping the next update will enable comments. Hit that source link (or just open up the App Market) to grab it for free, and jump on past the break to see how your fellow city dwellers feel about this marvelous invention.