I've only ever waggled while passing either my parents or girlfriends villages, but on reading this thread, I now promise to be friendly and visible, by waggling when I see other aircraft out in the open FIR. Might have to draw the line at waggling on short final though...
I wonder if we can 'out' folks who don't? I've got that line from Life of Brian running through my mind now... " 'ere, this bloke won't waggle!"