iMagnify!

iMagnify! is a handy application, especially for professionals who deliver presentations or perform demonstrations for an audience.

You can use iMagnify! by starting it up and placing it in any convenient place on your screen where your audience can see it when projected. With that done, you simply select the magnification level that you desire, adjust the window to the size width and height that you prefer, and then leave your mouse at the top left corner of the portion of the screen that you'd like to magnify.