Ctrl + click a link, to open link in a new tab
Ctrl + Shift + click, to open link in new tab and switch to it
Shift-click , to open a link in a new window
On Windows, use Ctrl-Tab to move to the right
Ctrl-Shift-Tab to move to the left.
press Ctrl and any number key between 1 and 9
Ctrl-1 jumps you to your first (left-most) tab
Ctrl-5, for example, jumps you to the fifth tab from the left
Ctrl-9 jumps you to the right-most tab
Ctrl+T to open new tabs
Ctrl + Shift + T opens previously closed tabs
Alt-spacebar-X
Alt-spacebar-N to minimize Firefox (or any active window).