You can't do much but read this story :)

http://www.thoughts.com/RebbyPDX/muslims-always-parked-in-my-parking-spot-until-i-stopped-them-cold-by-rebekkah-ann-barnard-1

The same thing happened to my neighbor. Someone repeatedly parked in his rented spot and he finally decided to park on the drive way to block the violator.