Two of the biggest problems facing cities are graffiti and illegally parked cars.

Here is a combination solution:

Why not allow the Graffiti Gangs to paint on illegally parked cars without penalty.

The result would be a sharp decrease in the number of illegally parked cars. The taggers would then have a legitimate place to practice there instinctive marking behavior so there would be a concurrent decrease in the amount of illegal tagging.

Hey its worth thinking about.