I am a nodder, That is, I like to nod and get a nod back from other bikers. Some do, some don't and it's ok either way.
However I can't get my head round bikers that stick their leg out to cars (or bikes) that they pass. Have you seen that?
Not only does it look naff (in my humble opinion) it also suggests they are too frightened to take a hand off the bars to give a friendly wave. Or am I missing something?