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).
The first and only download manager/accelerator built inside Firefox!
The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
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...
Xmarks is the #1 bookmarking and open tab add-on. Keep your bookmarks, and open tabs backed up and synchronized across computers and browsers. Mobile phones with Premium access. Utilize LastPass to sync passwords!
United States English Spellchecker for Firefox, Thunderbird and SeaMonkey by Kevin Atkinson and Geoff Kuenning.
To enable, right-click in a multi-line text box, select "Languages", then "English (United States)".
The extension previously known as GooglePreview. Inserts preview images (thumbnails) and popularity ranks of web sites into the Google, Yahoo, Bing and DuckDuckGo search results pages.
Fasterfox Lite: Performance and network tweaks for Firefox, without the Enhanced Prefetching. This is a fork from the original "Fasterfox".
Stay on top of the information you care about with the Yahoo Toolbar. Preview your favorite sites, like Facebook, Gmail, eBay and more, from any page you’re on.
URL Fixer fixes common typos in URLs entered in the address bar. It will fix errors like "google.con" or "youtube,com". You have the option of being asked to confirm corrections before they are applied.
Get international weather forecasts from AccuWeather.com and display them in any toolbar or statusbar with this highly customizable and unobtrusive extension.
Add useful extra features to Gmail, like hierarchical labels, an unread message icon on your browser tab, file attachment icons, and more.
A compilation of some of the best Greasemonkey user scripts for YouTube in one interface.
Collections are groups of related add-ons that anyone can create and share.Explore Collections