I really only find one kind of harasser out there: The teens in Jeeps. Ok, there are a few other jerks out there too, but really it's the car full of teens goofing off that I am confronted with on at least a third of my rides. Night rides are worse for this, because my lights are more visible, evoke more of a reaction, the cover of darkness emboldens harassers, night times are more "goofing around" time for teens and 20-somethings... a perfect storm.
On the other hand, traffic is minimal at night, so I still feel pretty safe.
Anyway, there's no good way to handle them. I lose my cool once in awhile. I ignore them most of the time. Sometimes they startle me and I stew about it for the next mile or two down the road, but the whole reason they feel emboldened to do this sort of thing is because they rightly recognize that they have the ability to disappear into the road ahead quickly.
A couple of times they've been met with a stop light and I find myself alongside them. And then what? I've tried to engage in a "Why would you do that?" conversation but have never gotten a good answer, mostly because there is no good answer. But usually the window rolls up as I approach, and I'm not inclined to want to start knocking on the window, risking being seen as the aggressor.
Riding in groups, even with one other cyclist helps a little. We're even more the target, sometimes, but at least have each other to complain to for the next mile or so rather than being left alone with our thoughts.
I've fantasized about passing a parking lot a mile down the road and seeing the car there. Only happened once, but again, then what? I don't carry a pencil and paper. I'm not going to vandalize a parked car. Even if I encountered them inside a convenience store, what conversation would I have? "Why would you do that?" I already know there's no good answer to that question.
Nobody much cares. It will keep happening, because there will always be idiots. Idiots existed long before bikes and cars, and we haven't evolved past them continuing to exist. It will always be fun to some cars full of kids to shout incomprehensible things as they pass by at 2x to 3x the speed of the cyclist. Cyclists will always stew about it for the next mile or two down the road.
True road rage incidents are less frequent. I've only experienced two, and only one of them felt the least bit dangerous. They both were over in seconds, and the offending vehicles were gone before I knew what was happening. It's a problem, for sure. One incident is a problem. None would be wonderful. But again, there will always be idiots.
Still we ride... or at least I still do.