(Note: Picture from this guys blog post. He endorses waving, but it sounds like he hasn't been riding long... give him a few years.)
I don't generally do the motorcycle wave. You know, how there's some universal courtesy that all motorcyclists wave at all other motorcyclists. I could understand it if you lived in a time or place where there were very few riders, and seeing another one was an uncommon event and there was a good chance that yourself and that other rider were kindred spirits, or had some common thread or understanding that was shared by few others.
It's not like that though. At least not any more, and not around here. There are thousands of motorcyclists even in my relatively sparsely populated little corner of the world. I probably wouldn't even like most of them! Ok, just kidding, that's probably not true. Still though, I really doubt that I have more in common with most of the guys that wave at me, than I might have in common with the person in the car behind them.
You don't see every guy driving a chevy pickup waving at every other guy in a chevy pickup.
Now, maybe the world would be a better place if you did see that. Maybe I'm a jerk for putting negativity into the world, when all that's required is a simple acknowledgment of the person who's waving at me. But seriously, it's a hassle. It happens so frequently that I just get tired of it. Especially during The-Big-Trip last month, where we were on the road for 17 days. I must have ignored like 400 motorcycle waves (but i probably waved back 150 times). Anyway, it just seems silly to me at this point.
I'm more than happy to be courteous and pleasant to any motorcyclist that wants to talk to me at a gas station or whatever, but the wave, I dunno, I'm over it.
Now, sometimes, when i see an adventure/tour bike, loaded up and obviously in the middle of a long trip, I'm more inclined to wave to that person. The reason is that now we've narrowed the crowd down to a small enough subset that myself and that person probably do have something in common.
Anyway, long story short: I'm a jerk and i think the motorcycle wave no longer means much of anything and so i don't do it.