Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
LastPass, an award-winning password manager, saves your passwords and gives you secure access from every computer and mobile device.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
AddThis for Firefox is the best add-on to make sharing and bookmarking simple. Have all your favorite web 2.0 social networking, bookmarking, blogging, and e-mail services at your fingertips. Share any page, anytime, with anyone.
Shareaholic is the easiest way to share & bookmark great content from anywhere on the web from one simple ALL-IN-ONE add-on. Works with Facebook, Twitter, Pinterest, Google, LinkedIn, E-mail and 200+ additional services.
AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.
ShareThis for FireFox makes sharing simple. Share anything on the web with your friends on 45+ social sites including Facebook, Twitter, Email, Digg, Reddit and more. Track top trending shares by site and automatically save content to your ShareBox.
Collections are groups of related add-ons that anyone can create and share.Explore Collections