I figured slowing down when being tailgated is the safe option. As if the tailgater does hit me its at a slower speed. Never gone to lengths Matt did to p*#s them off (brilliant btw :) ) but I do love doing 25mph on a 60mph road winding them up, they deserve it for driving reckless imo. Also when I attended a speed awareness course this is how they tell you to deal with tailgaters, slow right down and leave a big gap between you and the car in front.
I had a mate who drove a battered Vauxhall Calibra a few years ago. I mean there were more dents and dings in it than straight lines. he used to deal with tailgaters in his own way, he would wait till he pulled up at a red light with the tailgater behind him. Then when the lights turned green he would select reverse and bump straight into them, denting his car (but he couldn't care less) and sometimes doing quite a bit of damage to the car behind but he would then just race off leaving the tailgater stunned and with a damaged car. Now I'm not condoning this but I have to admit it made me chuckle