The aptly named at the University of Washington team has released, for free, two mouse cursor control systems for that make locating the mouse on a target and interacting with it easier by changing the way the user interacts with the display.
ACCESSIBILITY IN ACTION:
The group's first cursor system is called and is claimed to make clicking accurately on an onscreen object something like 23% faster (the group has that explains the science behind this technique).
The system creates a circular "locating" cursor that is sized according to the user's ability to control the mouse -- the less control the bigger the locating cursor and vice versa. Once the locating cursor is over the target, clicking any mouse button locks the locating cursor in place and the area under the circular cursor is shown enlarged.
Subsequent mouse movements control a standard cursor within the zoomed area and any "mouse up" event (i.e. the end of a click or the end of a click and drag) within the zoomed area is sent to the corresponding coordinates on the normal-sized screen and the locating cursor is shown again.