GeoGraffiti describes itself as a "free verbal message board for exchanging location-specific community information." In essence it is a location based social community built on Google Maps - but with a big difference - users geographically tag a Google Map with voice messages from their cell phones.
The video below has a good example of one possible use of GeoGraffiti. Suppose you are on your way to work and you hit traffic, how do you warn other drivers? Well with GeoGraffiti you can use your cell phone to leave a voice message on a Google Map informing other users of the problem.
The big advantage of GeoGraffiti over other social community Google Maps mash-ups is exactly this kind of situation. When a user does not have access to a computer keyboard they can still geographical tag a Google Map with a voice message. This video gives other examples of how GeoGraffiti could prove invaluable to its users:
GeoGraffiti certainly has the features to make it a useful social sharing site. Users can define the geographical area they are interested in, they can become fans of users whose messages they like, they can refine their search of voice messages by 'most popular' or 'most recent'.
As with all social community sites GeoGraffiti is dependent on users. If the site garners a number of enthusiastic early users this site could really take off.