This is a great post on Search Engine Journal from Ann Smarty about some great Firefox add-ons that help you share and navigate content. I really like AddThis, but Shareaholic is a close second.

One of the reasons why I use FireFox is because of the addons- they offer a unique web experience that has not been matched by internet explorer 8, safari, or even Google Chrome.

See the article here: 8 FireFox Add-Ons That Unite Multiple Social Media Networks