I talked about these elsewhere but here might be better. Search "Wireless Optical Pocket Pen Mouse". Apparently they work on most surfaces. You don't need a tablet. I have one of these I got real cheap and haven't used it yet, I need to. I was thinking of drawing on my chest or stomach in a drawing program. Since it also works as a mouse it would be easy. Also I think people can very accurately move stuff around on their bodies so it would be natural. A lot easier than being forced into one position on a drawing tablet or hunching over a screen.