As good as the trackpads on Apple's portables are, they can be a little slower to use than regular mice. Sidetrack is an increadibly useful addition to any Mac laptop. Installed as a preference pane, it adds functionality to the trackpad, converting the right-hand edge into an up/down scrollwheel and the bottem edge into a left/right scroll. The pad itself can also be set to perform a left- or right-click, or a click-and-drag action when you tap on it. Speed and sensitivity can be set, as well as scroll area size. This really is fantastic, and when you start to use it you'll realise how long it used to take dragging over to the scrollbar every time you wanted to move up or down a Web page or a document.
With Sidetrack it's easy, and it becomes second nature in next-to-no-time.