Unveiling 10 Hidden OS X Shortcuts

Years have passed since the first time I used my Mac. While using my Mac, by accidentally hitting wrong combination or purposely browsing for it, I'd discovered some hidden keyboard shortcuts.
Shortcut, as the name suggests, should bring us more productivity juice rather than drag us down. However, some shortcuts may suit you well, some may take more time for you to adapt; to adopt these new hidden shortcuts or to drop them, that's all depend on you.

Hidden Shortcuts for Mac OS X

I've tested these shortcuts on my Mac OS X Leopard with U.S. Keyboard.

1. Apple Logo

Shortcut : Option-Shift-K
Note. One of the symbols that can be drawn with simple keystroke, the famous Apple logo. Sorry, but I can't resist to put this as the first shortcut.

2. Zero Brightness

Shortcut : Control-Shift-Eject
Note. Instantly turn your display off without logging out from the system.

3. Adjust Volume Bar

Shortcut : Option-Shift-F4 / Option-Shift-F5
Note. Increase/decrease your volume bar by a quarter each time it's invoked. This is particularly useful for fine tuning Mac with bombastic sound system.

4. Double Buffer

Shortcut : Control-K (Kill) and Control-Y (Yank)
Note. Like, Cut and Paste, combination of Kill and Yank can help you organize your text easily. Cut followed by Kill grants you double text buffer.

5. Home and End

Shortcut : Control-A (Home) and Control-E (End)
Note. This is pretty much the substitution for Windows button HOME and END. Pressing Command-← or Command-→ performs the same action.

6. Delete and Backspace

Shortcut : Control-D (Delete) and Control-H (Backspace)
Note. In Windows, we've got two buttons for this : DEL and BACKSPACE. You can use Fn-Delete to perform forward deletion while the button Delete acts as Backspace.

7. Related Messages

Shortcut : Command-Shift-K
Note. Selects all related messages in the same mailbox.

8. Open Address in New Tab

Shortcut : Command-Enter
Note. While highlighting address bar, pressing this shortcut will bring up new tab of that selected address.

9. Google Search Box

Shortcut : Command-Option-F
Note. Quickly jumps your cursor to Google Search Box. Saving your mouse click as well as your precious ticks of seconds.

X. Zoom

Shortcut : Command-Option-[+] (Zoom In) or Command-Option-[-] (Zoom Out)
Note. Zoom in/out your display; making tiny objects looks huge.

Using the Hidden Shortcuts

As I said earlier, to drop or to adopt all depends on you. Shortcuts are in nature meant to help you save your time. If you don't feel comfortable with using shortcuts, it doesn't make sense for me to force you. However, I've tried our best to put short notes on each shortcut as a little hint.
There's high possibility that you may have another favorite shortcuts, I'd always love to know your opinions. Let's hear your choices and any I missed in the comment box.