I just save up a few choice insults. I get crap fairly often for passing the row of vehicles stopped at the lights on the left.
My favourite at the moment, and one I got to use last week is "Read rule 151* of the Australian road rules and if you don't like it, catch the fucking bus, you gonnoreah ridden, scabby whore/pedophile."
(*A bicycle may pass moving or stationary traffic on the left)
I'm yet to actually have response from the driver, but I have had a few occupants of other vehicles have a chuckle at that outburst.
A few weeks ago I had a cigaette butt flicked at me by a P plater stopped at the lights, so I stopped, picked it up and threw it, still lit, through the open passenger window. The guy (in a V8 ute no less) behind him applauded me.
If someone does something delibrately dangerous I'm all up for vehicular damage. Adelaide is far far better than Sydney, but if someone's going to delibrately endanger my life, there's got to be consequences. They might kill the next person. Our legally viable options are very limited, so I opt for legally dubious and immediate retribution. It might not do anything for cyclist/driver reconiliation but if you're going deliberately try and hit me with your car:
a) our relationship has gotten to the point of potentially homocidal activities. It probably can't get much worse.
b) if you get away with it this time, what's coming next time I solw you down?
and c) anything I can do that might mnake you think twice about it next time is good.