One of the handy tools to have is virtual magnifying glass. It can be a solution when one need to enlarge only a portion of the display. For example, if you want to show some video or demo on a large screen, and the application does not support making it visually bigger. Or it can be a necessary tool for people with low vision.
There also exist a portable version (with portable apps).
Note:
- different browsers might give different results (eg. video might work with firefox but not chrome)