I flash for hazards - accidents or debris on the road for example - but not for speed cameras. I personally think that being fined $100 is more of a deterrent than someone flashing their lights at me and hoping I see it. I've been caught speeding before, and been fined, and while it's annoying, I have only myself to blame. I won't help others to get away with speeding - eventually they'll wise up, or they'll lose their license, either outcome makes the road safer.

I have on occasion pulled over to ring the non emergency line to report cars driving well over the limit or driving recklessly. I tell them the plate number and the direction they were headed, and I can only hope that they get caught before they kill themselves or someone else.