unfortunately Firefox is slower than opera and chrome. But despite this Firefox is much better than other browsers and here is why.
Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Orkut, and many, many other sites. You can even customize Firefox and other programs themselves.
Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more...
Integrates location bar and search bar into one. Shows search and url suggestions. Quickly switch search engine using search keywords. Provides different auto-complete popup styles for compact displays.
Foobar combines Firefox's search and address bars into one easy-to-use search and navigation bar.
Adds icons to your Firefox menus. Choose from the built-in icon sets or import your own.
custom additions to Stylish extension.
brings back features from 0.5.9 and adds new features
I can't be bothered to change SC, so amo will allow it to be uploaded
Use identicons to automatically generate favicons for sites without one.
Note from Mozilla: This add-on has been discontinued. Try FXChrome instead.
Chromifox Basic is a coat of chrome for Firefox.
Fission combines address bar and progress bar (Safari style). This makes the progress bar more visible and allows for a nice visual effect.
Note from Mozilla: This add-on has been discontinued. Try Colorlicious instead.
Change Firefox to Any Color and create your own personalized theme.