Lets face it, some hand motions are just more natural than others, and operating a standard mouse isn't one of them. With the SafeType mouse you can hold your hand in a natural position, a grip with the thumb facing upwards, using your first two fingers to click the buttons, and with your thumb on the scroll wheel. According to the SafeType people, scientific test have proven that this position reduces stress on the hand, arm, and neck, lowering the chance of carpal tunnel type injuries.
Coming in two different sizes, the SafeType mouse is available now for $74, but only in a right hand drive version. As someone who has always used my left hand for this type of thing, I guess that counts me out.