What fun. Ever looked up in a Wal*Mart parking lot? In the one near my home, I once stood in place at my car and counted 12 cameras in my view without turning my head. Then I turned and came up with a simillar number.
It's probably not nearly as effective as aiming cameras back at them, but I've gotten some interesting reactions by waving back at the security cameras in L.L. Bean. They have the store covered with the little black half-sphere cameras that are supposed to keep you from knowing which way they are looking right now. (Hint: there's a darker line about an inch or so wide, and somewhere on that line is a circle - the lense.) Security doesn't seem to like it when you notice that the cameras are always pointed at you, and wave back. In fact, they may find it necessary to follow you to your car if you do.