Yogaballs as Mice

Using a mouse, even a nice one, is a limited-range/limited-muscle tedious effort. Manipulating the cursor by leaning different directions (or bouncing to double-click!) on your yogaball/seat might be a welcome break and a much more full-body experience... While it probably wouldn't be used all the time -- it could allow people to get into the flow more and maybe even think more physically when they're using the computer when they choose to use it.

Also, it would allow the user to leave both hands on the keyboard while moving the cursor -- mouse-keyboard commuting is a very common slowdown and physically aggravating factor.

Technical considerations:

From a functionality standpoint, the "yoga ball pointing device" would be most similar to the "pointing sticks" found on some laptops... where the computer moves the cursor according to the force, not location (eg: leaning farther over, moves the cursor faster)

There would probably have to be a way to engage/disengage the yoga ball -- otherwise inadvertant movements would move or "click" the cursor.