As with most operating systems of the last decade or so Mac OS X contains options for accessibility by people with disabilities. What users may not realize is that some of these options are extremely useful to anyone.
OS X puts these functions in the Universal Access pane of System Preferences. This article will concentrate on a few options in the Seeing and Keyboard tabs.
The first item that is certainly of use is the zoom feature. Pressing Command- Option 8 zooms in on the screen around the mouse cursor. By default graphics are smoothed after the zooming takes place, so images that would otherwise appear pixilated still look decent. I often use this feature when watching low-quality web video. Rather than putting up with a tiny postage stamp sized video I simply press the short cut key and watch it much closer to full screen. Once in zoom mode the magnification can be adjusted by pressing Command- Option-minus or Command- Option-equals.
The Keyboard tab has features designed for people who have difficulty typing. However, one of the options in Sticky Keys is very useful for people creating screen casts. With Sticky Keys open and the option "Display pressed keys on screen" checked, the symbols for modifier keys, command, option, control, or shift, appear on the screen when they're pressed. In tutorial situations and with new users this is useful to provide a visual cue to go along with the name of the key being used.
For people with no challenges using a computer the Universal Access pane may be the last place they would look to add useful functionality to OS X. As you can see, there are some options, however, that can improve the computing experience for anyone. Hopefully people will be inspired to explore further.