I have developed an android application, by which the user can take a photo of a graffiti on the street and send it, along with the GPS coordinates of the graffiti location to a server. In this way the user is able to see all graffities on a google map from his mobile. Check out the application at: https://play.google.com/store/apps/details?id=stratos.greece.graffiti

Moreover all graffities can be seen on the internet at the following website: ??? ?? graffiti

As you may have seen both the android application and the website is in Greek, but I can translate it in English very easily and adjust the map to display the area you like, if you wish to use my app for your graffities.
Thank you