1. Zoom your screen. Hold down the Control key while scrolling up on your mouse (or performing a dual-finger up drag on your trackpad). Your entire screen zooms in. Control-scroll (or drag) down to zoom out.
2. Scroll through your Apps Press and hold the Command key then press and release Tab to display your active Applications. Scroll through your applications left (scrolling up) and right (scrolling down). When an Application is selected, you can move your hand from the scroll button on your mouse to the keyboard to press "H" to hide the application or "Q" to quit it. Release the Command key to switch to the selected application.
3. Scroll horizontally. In applications with both vertical and horizontal sliders such as, say, Preview, press Shift while scrolling to scroll horizontally instead of vertically.
4. Open pages in new tabs in Safari. Instead of right-clicking a link and selecting "Open in New Tab", just scroll-button-click a link instead. If you have enabled tabbed viewing in Safari (Preferences -> Tabs -> Enable Tabbed Browsing), your link opens in a new tab.
Thanks, Fritz Laurel.