Mattresses and Postural Supports
Mouse, Trackball, Touchpad, or Other Pointing Device
Tips for Purchasing an Ergonomic Mouse: Look for a mouse that has a contoured design in order to allow your forearm and wrist to be in a more anatomically neutral position. This reduces the risk of repetitive stress injuries. An additional feature to look for are size options to fit your hand appropriately. I do not generally recommend trackballs, as they tend to require the user to perform repetitive motions, leading to the possibility of repetitive stress injury.
Following are some links to companies that sell ergonomic mice:
In particular, this company sells the Humanscale Whalemouse, which is adjustable for different sized hands.