I’m using the Firefox beta and I like it very much. I’m seeing a lot of blog post with people’s top ten extensions, or 20 extensions that are great for productivity, and many other ways of saying, “These extensions are great”. I’m going to list my own extensions, some which may not be useful for others, and some that could help a lot.
Adblock plus

Adblock does what it does: it blocks adds. It’s simple to use, just choose a filter subscription which updates what adds to block, and you’re good to go. If something is ever blocked by Adblock plus that you need to see, middle click on the little Adblock plus icon at the top right.
Better gmail 2
This extension is one that I used mostly just because it forces an SSL connection, so that my email doesn’t get read by whatever packet sniffers there are. Call me paranoid, I just like my privacy. Otherwise it just makes gmail looks different.
Blocksite


This extension allows you to block sites. Not that obvious, isn’t it. It allows you to have a blacklist, and will disallow you (or someone else) from going to a website of your choosing. Wildcards can also be used, so if a website gets rid of the www when accessing a different webpage, then it will still be accessible unless using wildcards.
Colorful Tabs

An extension that makes all tabs a different color. it looks pretty, and it’s plain and simple.
Configuration Mania

Using Firefox a lot, I like to customize it to my liking. Rather than go and snoop around in about:config, it can be much easier just to install this extensions and select what you want. Don’t like the width of the tabs? Go to the appropriate selection and set it to 0. As long as you have a bit of knowledge on how firefox works,you’ll be able to set most of the options without much of a problem.
Download Helper

I’m sure most people would like it if they could download all those funny youtube movies. There are many services that can do so, and I prefer to use this one. It allows you to download the embedded FLV file in the youtube webpage, as well as in other websites. The only problem is that you have to download a program that plays FLV files, or convert it.
IE tab
A useful extension for those websites who are still stuck in the past. It uses the Trident rendering engine which IE has in order to display webpages that don’t display properly in firefox. This is an extensions which I have been using less and less, but it still is useful for those banking sites who hired a “frontpage expert” to design their site.
Nightly Tester Tools
Being a beta 3 user, I often find extensions that work only with Firefox 2. Many of those extensions can still be used, sometimes working like it should, sometimes with issues, and occasionally not working at all. Now, I can install any extension I want without Firefox telling me I can’t because of compatibility issue. By the way, every extension I’ve listed is compatible in at least some way with Beta 3
Stumbleupon

With 4.5 million users, I don’t think I need to describe this. Try out the demo here.
Web Of Trust
Web of Trust, or WOT, lets users choose on a scale what they think about certain websites, with the criteria trustworthiness, vendor reliability, privacy, and child safety. Although not very useful with day to day browsing, this can be important if, say, you’re buying something online from an unknown websit, or you’re trusting a wesite in some sort of way to not do anything you don’t want it to do, and you want to know how reliable it is. Here is a search for a defragger.

These are the extensions that I have installed and use at least semi regularly. Ever since I’ve switched from IE 6 to Firefox 1.5, I’ve never looked back, and extensions are a major reason why.