https://addons.mozilla.org/en-US/firefox/addon/9427
Just found this one. Its a skin/theme that makes FF look like Google Chrome. The idea of this was to give me more real estate in my screen as it cuts out the completely useless titlebar above the address bar, Ive no idea why you need the title up there anymore as page titles are already displayed on the tabs. I cant use it because of a plugin for a password manager I use has a button that show up weird.
This is an experimental add on whic means you need to register and log in to download it. Nice blue colours BTW
Theres a full guide to making it as close to Chrome as possible here.
Extendably.com