I think I'm hijacking this thread, but this reminds me of one of my favorite pastimes. We live in a small historic community (300 folks) that all kinds of tourists visit on weekends. Our house sits on a corner of the main (and only) street, and an alley that leads to some small shops. We have a stone parking area big enough for three cars (our cars) along the side of the alley. Often on weekends we'll come home and find a strange car plopped in one of our spaces. What I do is pull our car in lengthwise in front of theirs, which blocks their ability to get back onto the alley. Then I go inside our fence and sit on the back porch and wait for the inevitable visit from the car's owner. The first thing I always say is "What makes you so special that you can just park in a private space whenever you want to"? They usually say that they thought it was public parking - right in front of my Private Parking sign, or that they were only going to be a few minutes. If they are polite,I let them out right away, if they are a pain in the ***, I sit there and stare at them for awhile, to see what they will do next - sometimes it's pretty amusing!