Mozilla Firefox Shortcuts -

Ctrl + Tab or Ctrl + PageDown - Cycle through tabs.
Ctrl + Shift + Tab or Ctrl + PageUp - Cycle through tabs in reverse.
Ctrl + (1-9) - Switch to tab corresponding to number.
Ctrl + N - New window.
Ctrl + T - New tab.
Ctrl + L or Alt + D or F6 - Switch focus to location bar.
Ctrl + Enter - Open location in new tab.
Shift + Enter - Open location in new window.
Ctrl + K or Ctrl + E - Switch focus to search bar.
Ctrl + O - Open a local file.
Ctrl + W  - Close tab, or window if there's only one tab open.
Ctrl + Shift + W - Close window.
Ctrl + S - Save page as a local file.
Ctrl + P - Print page.
Ctrl + F or F3 - Open find toolbar.
Ctrl + G or F3 - Find next...
Ctrl + Shift + G or Shift + F3 - Find previous...
Ctrl + B or Ctrl + I - Open Bookmarks sidebar.
Ctrl + H - Open History sidebar.
Escape - Stop loading page.
Ctrl + R or F5 - Reload current page.
Ctrl + Shift + R or Ctrl + F5 - Reload current page; bypass cache.
Ctrl + U - View page source.
Ctrl + D - Bookmark current page.
Ctrl + NumpadPlus or Ctrl + Equals (+/=) - Increase text size.
Ctrl + NumpadMinus or Ctrl + Minus - Decrease text size.
Ctrl + Numpad0 or Ctrl + 0 - Set text size to default.
Alt + Left or Backspace - Back.
Alt + Right or Shift + Backspace - Forward.
Alt + Home - Open home page.
Ctrl + M - Open new message in integrated mail client.
Ctrl + J - Open Downloads dialog.
F6 - Switch to next frame. You must have selected something on the page already, e.g. by use of Tab.
Shift + F6 - Switch to previous frame.
Apostrophe (') - Find link as you type.
Slash (/) - Find text as you type.