Finding a way to channel road rage without going berserk isn't easy -- just look to Gandhi's example, after he got cut off, and only shot the guy in the leg. Get back at terrible drivers semi-anonymously, with Carpong.
Basically a Twitter for incensed drivers, Pong lets you tell other motorists exactly what you think of them by using their license plate info as an e-address to send brief messages expressing your ire, as you receive your own healthy stream of invective for smashing into people while typing and driving. The setup's simple: sign up your plate info, do the same for any car you want to comment on, and tell them whatever you want in 250 characters ("STOP doesn't mean drive fast and be a douche", "use your blinker or I'll kick you in the face next time", etc); if they're also signed up, your reportees'll get an email alerting them of the note, revealing your username and license info, so you should definitely use it to give those cops what they've got coming. So far, there's been a healthy smattering of message action, from weather-related musings in Colorado ("apparently 1 inch of snow makes 90% of drivers 100% retarded"), to parking lot faux pas in Virginia ("I was sitting in my car when you slammed your door open into it with no remorse. Try not to suck so much in the future"), to generic comments in Ohio, i.e. "go bearcats", either a response to a Cincinnati bumper sticker, or a desperate wish that a pack of feral animals kill said driver.
If you're into stalking, you can search for people's license plates and "follow" them to see what sorts of things people are saying about their follies -- like that dude Gandhi popped, and just laugh and laugh about how much trouble he's having with his clutch.