I bought a Trackbar Emotion for use at home. At work I have use of a Contour RollerMouse, but the Trackbar Emotion is a more affordable option for less intensive home use. The Trackbar removes the need for a large arm movement between mouse and keyboard. Compared with the Contour equivalents, the Emotion pads for resting ones hands are smaller and have a hard surface. It's fine for an hour or so, but I wouldn't want to be using it all day in an office.
As noted by another reviewer, one irritation is for the pointer to occasionally flick across the screen in response to very little movement of the roller. On the other hand, the roller on the Trackbar Emotion has relatively limited travel and it can take several attempts to get the pointer across the screen when one intends to. The Trackbar Emotion is quite an old design now, from a time before high resolution wide screens were common.