How about using iSight to find my face, locate my eyes on the face, trace along the path of my gaze, and place the damn cursor there, when I push a pre-defined button? Mousing is tedious. I'd much rather push a button and just stare at where I want the input cursor to be.
Canon had something similar to this back in the day on their camcorders and cameras. It was called Eye Control, and the camera would focus on where you looked. They need to re-implement that!
Looks like I didn't thoroughly research the idea before posting about it - a similar solution already exists: http://www.postureminder.co.uk/