Easiest mousing/tracking device on wrist?

[GanChan]

I've been having some trouble with my "mouse" hand lately, but I can't tell whether my Logitech Trackman Marble or my Macbook Air trackpad is the cause. The Trackman is acting flakey anyway, so it's due for replacement. I've always liked trackballs, but if there's a more wrist-friendly or hand-friendly option out there, I'd love to hear your opinions/suggestions on the subject. (Some sort of ambidextrous product would be ideal so i could switch back and forth between hands.) Thanks....