Virtual Magnifying Glass
One of the best things about Virtual Magnifying Glass is that it offers two magnifying modes: classic and dynamic. In the classic mode the zoom window will follow the movement of your mouse cursor, and will disappear when you click your mouse or press a key. In the dynamic mode the zooming window can only be controlled using the shortcut keys, but it will not close when you click or use your keyboard.
More information: http://virtual-magnifying-glass.software.informer.com/