“I LOVE YOU!” is my current fave. If I catch up to the guy/gal (which I often do), I continue professing my undying love for them. I tell them how awesome they are in such terms that they become seriously fearful that I am a psychopath. If given the opportunity, I begin singing to them…. The Captain and Teniel’s “Muscrat Love” is my current favorite song to sing to the object of my affection. There’s a semi traumatized dude in a Mercedes convertible out there that still has nightmares about this lunatic on a pink bike that chased him around for 20 minutes telling him how awesome he was. Our parting exchange (the 4th in a series of interactions) consisted of me standing next to him at the light repeating the word “AWESOME” with many different vocal intonations over and over again for the entire 20 seconds that we were next to each other. I think he contemplated running the light. He certainly sped away with quite all haste.
Honestly, there is nothing I can say in a hostile tone, or in a tone of reason that will impact an aggressive or oblivious driver in any way. It is much better to instill fear in their hearts the way they do to the cyclists they encounter.
Bottom line: Hostility does nothing. No-one wants to hear our well reasoned arguments. Fear and insanity gets results for me.
Love, (not the fear and insanity type… well not the fear type.) 
Pete