If you give presentations then you might be interested in a new free tool from Sysinternals called Zoomit
Zoomit allows you to zoom an area of the screen and to draw on it. The zooming facility is similar to the Windows magnify utility and the same effect you can get from the Microsoft Wireless Laser Mouse 6000. The drawing facility is similar to the effect that you can get in the PowerPoint viewer with the rather important difference that you can draw on anything and not just PowerPoint slides. Overuse of the zooming facility can be a bit irritating for the audience but this still looks like an excellent tool.