Earlier quoted context omitted.
So you would type out the word "nod" once in a while, just like you would nod your head during a physical conversation? That's curious. I've never seen that before - I don't use chat/IM a whole lot though.
I think it's an IRC-ism since there you can type /me nods And the "/me" token will be replaced by your username and the whole "action" will be a different style (font/color/what-have-you) on some clients.
The same command works on Skype and does what one would expect. It's just not really advertised. Try typing /help in a Skype chat window.