With Pinned Tabs or App tabs, Firefox allows users to pin their favorite websites like Gmail, Facebook, Twitter, etc. You can keep these tabs open and work on other tabs, these tabs doesn’t occupy space on the tab bar and will open automatically when you launch Firefox. Till now to pin or unpin a tab, you need to right click on a specific tab and choose that option. A keyboard shortcut serving this should be much better, if you want that, Pin UnPin add-on adds that to Firefox.

Easy App Tabs, Double Click a Tab to Convert to/from an App Tab

Download and install this restart less add-on. After its install, you can use an Alt+P shortcut to pin or unpin the current tab. Advanced users able to pin or unpin current tab from Firefox’s developer command line tool by using “pintab” and “unpintab” commands. You need to install this extension for these commands to work.

Firefox Pinned tabs

Stack Tabs, Pin Tabs in Opera 11

If you’re already using Tab Mix Plus add-on, you don’t need to install this. You can assign a shortcut to Pin Tab/Unpin Tab by visiting TMP options>Menu>shortcuts.