Remember the days of the square-shaped mouse with only two rectangular buttons, with not a mouse wheel in sight? Those things were pretty torturous to use for any extended period of time, mainly because of their unforgiving design.
Perific hopes to eliminate that problem with a new wireless mouse/trackball that forgoes feature bloat in favor of giving your hands a comfortable user experience. The Perific Ergonomic Mouse & Trackball secret to success is that it can be used in a whole bunch of manners, ensuring that your hand isn't making the same gestures and movements over and over again. Remove its shell and it becomes a normal mouse, but movement is done via the trackball and you can hold it in a variety of different positions.
Further making it easier on your hands, there's two sets of buttons on either side of the mouse, so you can use it in either mode (with or without shell). The mouse designed to keep your hands free from crippling pain costs $119.