I'd prefer pin-on purely because I have no idea where I'd put a clip on.. as my clothes don't have places to clip stuff on to... But then again - we might need an accident book for the amount of people who may stab themselves with the pin! Also may be getting slightly school like and shit but... May be an awesome idea to get individual photographs of people with their cars? Would give us all something to do for a bit and what not, plus would be nice to look over after the event and then remember names-faces a little more. Just an idea that popped into my head .. Even just on an iPhone or