Combines the address and search bars into one like Google Chrome

Foobar

Foobar integrates the search bar's functionality into the address bar, making it easier to search/navigate and allowing the search bar to be hidden for more room on your toolbar. Be sure to check out all the options under Tools > Add-ons > Foobar > Options

I still wonder why they use Foobar as the name of the add on
http://www.foobar2000.org/



[Source]Firefox