I have been noticing a lot of "younger female" drivers in my town that seem to need to have the cell phone against their heads to survive.(insert blond with headphones joke here) I witnessed one that I was behind in traffic, pull into a parking lot, get out of the car and go into a store all with her phone up to her ear and not watching traffic, even when she nearly got run over walking to the store. I intentionaly drop a gear and rev my engine beside people who are on cell phones while driving. I think it should be against the law to drive and talk on a phone.( I have a tough enough time talking to my wife in the passengers seat while I drive. At least she is in the car with me and can say stuff like "you're going too slow" or "the light is green you know")
Before cell phones were everywhere people got along just fine without constant communication with eachother. Personally I don't have that much to say that I would need to talk to someone 24/7. That is the beauty of riding. No cell phone, no radio and if your pipes are loud enough you can't hear the ol' lady on the back much either.
I say keep revving and let them keep waving. Or maybe get a sticker that says "next time wave at me with all your fingers". At least if they are waving, they know you are there.