I had a similar incident to the OP's over the summer. I didn't get a chance to catch up and give him what for even though I tried. He buzzed me close enough and the situation felt threatening enough that I jotted down his license plate # as soon as I got a chance. I decided not to call, but my city has a traffic incident report webform that I filled out and submitted with a complete description of the incident, the vehicle and driver in question, and the license plate #. I never got anything more than an automated "Your submission has been received." kind of response, but in the recesses of my mind, there's some hope that the report of the incident somehow got noted on his record. I may have been wasting my time, but I figure that way if he does it again to someone and the result is a little less innocuous than it was with me, at least his prior behaior will have been noted.