A habit I just realized I have made for myself is that I tend to quote things.... a
lot. Not just on forums, but when I am talking to someone I'll use a quote to effectively show my side of the topic/argument. Doesn't work so well online though...
Also, when I stand and am not talking, I will put my hands together as if listening intently to one's conversation.
And I have another weird thing. I will do the hand gestures for "Okay, great."
which mainly consists of the O.K symbol and a thumbs up.