My standard answer usually seems to come across in a snide manner, but here goes:
I don't wave. Not that I think the wavers are retarded, but I think the wave itself is a retarded tradition. I mean . . . I don't wave to every Dodge Ram 1500 I pass, why every motorcycle? I didn't start riding to join a wave club, and I find it annoying that I'm expected to wave to every biker that I pass. Plus, I think it makes bikers look cheesy . . . riding around and waving everywhere they go, as if we're all in some secret club where we know each other.
I nod about 50% of the time. The other 50% I just ride on. I'm sure some folks get their feelings hurt, or think I'm a dick, but I have to take a one-man stand against all of the waving.
I will always stop and talk bikes when I run across another one at the pumps, I just don't like waving.