Logitech Optical Marble Mouse (USB/PS2) Review

I've been using one of these at work for the last month and it greatly reduces "mouse fatigue". It's amazing how adept and precise you can become with it.
Some have complained about the lack of a scroll wheel; go to http://simans.net/marble/ and download "Marble Mouse Scroll Wheel" then you will be able to scroll both horizontal and vertical when you hold one of the small buttons and roll the ball.
The only con I see with trackballs is that you need to clean them frequently because of our dirty hands.

Buy it here now!