HeadMouse is a wonderful and free means of accessing the computer using a standard low cost web camera to control the mouse cursor.
HeadMouse includes many advanced features, such as blinking or opening/closing the mouth to click and support for drag and drop actions.
For more able and older students, settings are easy to access and control using the HeadMouse itself. Menu options have animated visuals which help to make sense of the various tuning and mouse click emulation options.
HeadMouse integrates with a Virtual Keyboard from Indra which also includes support for switch controlled scanning.