Press Command-Q to close applications when command-tabbing. This is possibly the fastest way you’ll find to close several applications in quick succession.
Macs with remote controls can be put to sleep by holding down the play button on the remote.
Triple click selects a whole paragraph of text.
To select a block of text, click the start position, then Shift-click the end position. Significantly, this doesn’t just work in editing applications like Word (where you might be already doing it anyway), but it also works with non-editable text, such as a webpage in Safari.
In TextEdit, Option-click & drag selects a rectangle of text.
We all know Command-shift-4 to capture a selection of the screen, but don’t forget pressing the Spacebar will toggle between selection mode and select whole window mode.
Command click the jelly bean found in the top right corner of some applications to cycle through toolbars.
In Safari, Command-Shift-click a link opens it in a new tab and immediately displays the page.
The Option key is a hidden treasure trove. Experiment with it often. Here’s a few:
- Hold the Option key while clicking the Zoom button (green button, rightmost of three in the top left corner of windows) switches the zoom state of all windows in the selected application.
- Option-click the minimize button minimizes all windows in the application - and makes for a really cool animation (hold the shift key too if you want to slow it down to see it more easily).
- Option-click on a minimized window will restore all windows for that application.
- Option-click on a running application in the Dock hides the front-most application and brings the clicked application to the front (unless it already was).
- Option-click on the close tab icon in Safari, closes all other tabs. Handle this one with care - there’s no warning dialog.
- Option-arrow moves cursor by word. One for the Windows users who are used to using ctrl-arrow.
- When menus are selected, press the option key to reveal alternative functions. Eg: In the File menu of Finder, the Get Info item becomes Show Inspector which is like a context sensitive info pane.
Resource Link: http://www.applematters.com/article/20-useful-os-x-tips/