Wraparound is an application primarily intended for users with large and/or multiple screens, which allows the mouse cursor to "wrap" around the screens. Rather than spending time and energy moving the cursor across the screen, from one side to the other, simply drag it off one edge and it immediately appears on the other side.
Wraparound can handle even the most abnormal of screen-layout configurations, even allowing windows and other objects to be dragged though screen edges. And if you're worried about not being able to hit your menu bar or dock without the edge to stop the cursor, you can always turn off horizontal or vertical screen wrapping to suit your preferences. It also preserves screensavers and Exposé functionality with variable-sized non-wrapping areas at the corners.