When I drove a sports car we all waved at each other, then when I rode motorcycles we all waved at each other, then when I tried a recumbent everyone waved at me, and when I'm riding way out in the middle of nowhere and I see another bike I wave, but to be honest, I'm pretty much all waved out. I don't mean to be rude, it's just that seeing another rider pass in the opposite direction is such a common occurence anymore that it doesn't warrant a wave.