The most communicating I do these days is constantly saying "cheers" to the various groups of high school kids going to Trinity Academy in the morning, as they move aside when I ding my bell. In fairness, I think they are all starting to recognise me as the mental cyclist who is actually pleasant to them, because they are starting to move over even quicker than before when they see me coming. Maybe they are just surprised that someone gives them a vague portion of respect, since they likely don't get it during their school day.
Other than that, I've tried the "nod" to other cyclists, but I invariably nod to people who don't nod back, or people nod to me too late for me to respond. I'm a total failure in that respect.