I'm a huge fan of Zoomin, and have promoted it before on my site and I use it ALL THE TIME in Presentations. Bryan Ressler sent me a link to his UltraMagnifier .
- 1, 2, 4, 8, 16, or 32-times magnification
- Full multiple-monitor support
- Gridding of pixels (to facilitate counting pixels or checking alignment) in white, black, gray, or any user-defined color
- Update on a timer, on mouse movement, freeze, and timed-freeze modes
- Pixel-color display with choice of display formats (and color swatch)
- Save magnified image as BMP or PNG
- Copy magnified image to clipboard
- Printing with Print Preview
- Window features such as Stick to Screen Edges, Stay on Top
It's got everything that Zoomin has, and more! Very nice.