I often thought about rigging up my brake lights to a switch so I could make it appear to the tailgater that I've slammed on my brakes without actually doing so (because actually hitting the brakes could end up with the tailgater ramming into me). It's almost certainly an illegal modification and if someone ended up dead (such as the tailgater panics, hits the brakes and loses control and hits another car) because of it, I'd have a hard time dealing with that.
So I've given my car to charity. You all can have the highway wars. I live in the city and walk or take transit everywhere now. It's amazing how much lower my stress level is and how little I miss the places I use to drive to now that I've found lots of new places to go to. I know most people don't want that, but it works for me.