These are Add-Ons I use whenever converting someone new to Firefox, as well as those I use personally -- ranging from Privacy to Web Development, plus a few that make the web easier to navigate too.
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.
The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.
Collector's Note Very useful for making webpages designed for specific browsers work with with Mozilla. A surprising number of pages will still only allow access from Internet Explorer, with this add-on, you can fool the server into thinking you are using Internet Explorer and have access to the website from the comfort of Firefox or Seamonkey.
Remove or manage a new and uncommon kind of cookies, better known as LSO's.The BetterPrivacy safeguard offers various ways to handle Flash-cookies set by Google, YouTube, Ebay and others...
Latest updates: See bottom link 'version history'!
CodeBurner is a Firefox add-on that integrates with Firebug, to extend it with reference material for HTML and CSS.
Never lose anything you type into a web form again! Lazarus securely auto-saves all forms as you type, so after a crash, server timeout, or whatever, you can go back to the form, right click, "recover form", and breathe a sigh of relief.
Dead pages, broken links, the scourge of the internet. Powerhouse sites like Slashdot and Digg can bring a server to its knees. What do we do when a page is dead but we still want to see it? Call in the clerics, and perform a resurrection...
Collector's Note Have you ever been going through your History, found a page that you forgot about, clicked the link and been given a "Page Not Found" "Page Moved" or other error? Then this is a needed add-on for you! Using a variety of CDN's (Content Distribution Network's) as well as the Internet Wayback Machine, Archive.org and Google's Cache -- you can view an "expired" website from a variety of dates and times.
Collections are groups of related add-ons that anyone can create and share.Explore Collections