Alt-Left Arrow: Sends you back to the previous page you were viewing. Alt-Right Arrow, of course, takes you forward one page.
Ctrl-F: Brings up the Find tool, which works dynamically (i.e. as you type). Then I press F3 to jump to the next instance of my search item.
Ctrl-T: Opens a new tab. Note that you can start typing a URL immediately upon doing so, as the cursor automatically appears in the Awesome Bar.
Ctrl-Tab: Switches you to the next open tab. Ctrl-Shift-Tab takes you back a tab.
No ‘www’ prefix: Are you still typing ‘www’ at the beginning of every Web address? Guess what: The browser doesn’t need it. So the “shortcut” here is to just leave it off. Type pcworld.com and see for yourself.
Okay, your turn: What Firefox shortcuts do you use most? Hit the Comments and share your favorites.