There's no shortage of ergonomic peripherals these days, though we do kind of like the pointy shapes that come on this Designer Appliances AirO2bic grip-less mouse. Pronounced "aerobic," it specifically claims that it can prevent and even remedy Carpal Tunnel Syndrome.
The shape of the gadget lets you rest your hand in a vertical position on the base so you don't have to grip anything. Once you start moving your hand, the mouse should easily slide with it, though it may seem awkward at first. It comes with a optical sensor and Clickless software, though for $100, this thing better sing and dance too.
Designer Appliances Vertical Ergonomic Mouse [Bios Magazine]