Pie! My daughter can do the tongue thing. When ever she demonstrates, I have to remind myself that she is only 13 and has no idea what kind of comments she will be opening herself to pretty soon, if she continues.
I can do the writing backward thing too, with my left hand. I demonstrated this for my son just two nights ago after we were using his mini-whiteboard to practice math. I wrote something, he gave me a funny look and I told him to go check it in the mirror.
There used to be a TV weather guy who wrote things backwards as he stood behind a glass panel with the map on it; I always thought that was pretty nifty.