I take pictures of cars that are parked on the pavement so that wheelchairs/pushchairs/mobility scooters can't get past, or who have parked on dropped kerbs that I need to use (particularly in areas where they are few and far between and I have to do a 150metre detour to find another one), or who are in disabled spots with no blue badge. I usually take a couple of shots making sure to show (a) the problem parking and (b) the numberplate. Quite a few irate people, often passengers who have been left in the car, have got out and started demanding what I'm doing, the car is properly taxed, etc... but so far none of them have had it in them to hit a disabled woman ;-) For my part, I haven't actually posted any of my pictures to the net or sent them to the police or the department of transport or anything, I just like to think that the people seeing me take the photos might think twice in future.