TurboRing

Like the wheel on a scrolling mouse, the movable ring on Kensington’s TurboRing trackball lets you scroll through long documents with ease. To scroll the active window, you simply rotate the ring clockwise or counterclockwise. MouseWorks, an application that ships with the TurboRing, lets you reverse the scroll ring’s action, adjust scrolling speed, or disable scrolling entirely. The program also lets you customize the trackball’s cursor response and configure its three buttons.

The TurboRing’s sculpted gray case doubles as a handrest, and the angled ball and ring reduce stress on your arm and wrist. (Alas, the TurboRing is for right-handed users only.)