Why zoom? (I'm glad you asked.)
Sometimes, you want to show the whole Excel spreadsheet, and magnify portions of it quickly, to view the numbers more closely. Or, perhaps you're editing the layout of a brochure and would like to zoom-in fast and pan around to find a piece of content. Okay, how about web pages with video that don't let you view them full-screen?
The Universal Access features of Mac OS X let you quickly zoom-in (and out) to visually enlargre a portion of the screen. And, you can move the mouse to pan around the magnified screen.
Mouse over the general area you'd like to magnify. Then, hold down the Option and Command (Apple) keys together, and press '+' (plus). The screen will begin zoom-in on the area of the screen where your mouse if located. Type Option-Command-'+' again to magnify the screen further.
Type Option-Command-'-' to zoom-out, eventually to normal size.
There you go, citizens. A way to magnify your Mac's screen to heroic proportions!