"I'm not sure if this is exactly what you are looking for, but www.ergoindemand.com sells magnifiers that attach to the front of the monitor and magnifier the screen to a certain degree. The one's I have seen provide 200% magnification. For magnification that can be customized, I suggest looking at a screen mangification software program.

For more information about screen magnification software, visit www.magnifiers.org There is a wealth of information about magnification software and hardware. Hope this helps."