I found a mouse that attaches to your index finger with an elastic strap. You wrap it around your index finger and you control your mouse on the monitor with your finger. Plugs into a USB outlet, would really like to see if anyone would game on this.

Finger Mouse

I would think that if you're in the middle of a game and need to A) switch to a joystick with that hand or B) need to type something that whatever view you're using (first or third person) would be thrown wildly off the mark since the mouse is strapped to your finger. Seems very impractical for gaming.