Firefox Extensions

Firefox is not the most popular browser (yet) but it is the most customizable. The number of available extension for it is so great that there even some difficulty in finding an extension you need. This post is a list of extensions I found helpful. It also includes some tips about using the Mozilla add-ons site.

Lets start with how to search for extensions. If you already know the extension name you can search for it on the Mozilla site or if you have Firefox 3b5 you can use the built-in add-on search. It is not always simple however.
Firstly, especially if you use a beta version of Firefox, you may have compatibility issues. Unfortunately, if the add-on you want to install is not compatible with your browser version, the install button on the Mozilla site will simply not work. This is very easy to fix - you just need to open an account. When you are logged in, the site will still show that the add-on is incompatible but it will also offer to ignore this. Registering an account will also allow you to install experimental add-ons.
Secondly, despite the new look of the add-ons directory it is still hard to find good add-ons. The fact that an add-on is popular or even recommended doesn't always mean it will be of any use for you. For example - the AllInOne Sidebar is very popular - but I tried it and I saw no reason for me to use it.

And now to the extension list. The following list is the list of extensions I use. It is divided into extensions types.

1.Fighting with ads and other internet junk:
Adblock Plus - a very simply and highly customizable ad blocking solution.
Adblock Filterset.G Updater - Extra rules for ad-block. Update: It is no longer supported. For extra filters install EasyList+EasyElement filters.
Adblock Plus: Element Hiding Helper - Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
CustomizeGoogle - Allows to remove Google ads from search and other Google products.
Nuke Anything Enhanced - Remove any image or text from a page. The effect is temporal.
SafeCache, SafeHistory - Protect Firefox from some simple exploits.
CS Lite - A simple yet powerful cookie manager.

2. Customizing Firefox behavior and GUI:
Configuration Mania - Allows to change some normally hidden settings.
Download Statusbar - Firefox has a built in download manager, but it opens in its own window. This extension works in the status bar.
Forecastfox - Get weather forecast in your status bar.
Stop-or-Reload Button - This add-on merges the stop and reload button into one. It doesn't adds any extra functionality, but it saves space.
Fission - Moves the page load progress bar to the address bar. Both saves space and makes the progress more visible.
Personas for Firefox - Allows to change the Firefox theme without reloading. This add-on is in alpha version now.
Tab Mix Plus - Modifies and extends Firefox tab options. Very useful extension. You can get the latest beta version here.

3. Site specific extensions:
Better Gmail 2, Better GReader, Better YouTube - These three are collections of greasemonkey script built in an extension.
Firefox Universal Uploader - Allows to upload files from Firefox to 8 different photo/file sharing sites. Great for managing large collections of online files.
Smart Digg Button - See if a page you are visiting was dugg and if yes how many diggs it got.
Google Notebook - Integrates Google notebook into Firefox.
Google Reader Notifier - See how many unread items you have in the status bar.
StumbleUpon - A patent destroyer of any productivity and sanity. Install on your own risk. (It is also good for finding good sites and networking). The latest beta is here.
Googlepedia - Shows a relevant wikipedia article next to Google search results. You will need to block Google ads for it to work.
GButts - Shows links to Google services in a toolbar.
GMarks - a bookmark manager for Google bookmarks. GMarks includes a sidebar, a toolbar, a quick search with Home+Home similar to Google Desktop's Ctrl+Ctrl search, and full content search of your bookmarked pages.

4. Uncategorized (for now) extensions:
Copy Plain Text - copy text without formating. Especially useful for site owners.
Google Toolbar for Firefox - For me the main two things it offers are Google bookmarks and highlighting search terms on a page. It also allows yo to store your browsing history on Google servers.
Greasemonkey - A user script manager. You can read more about it in my post Modifying the net.
Nightly Tester Tools - If you use beta versions of Firefox, it is a good idea to install this extension. Besides other things it can override compatibly prompts.
MR Tech's Local Install - The primary goal of this extension is to provide the tools needed to install and manage extensions and themes locally. To do this the extension provides multi-extension installation support, hacking capabilities to the Extension/Theme manager windows, features to find and troubleshoot Extensions/Themes Build, GUID and Profile information.
Platypus - Create simple greasemonkey scripts. Knowledge of HTML is recommended but not required to use. You will need greasemonkey installed for it to work.
Prism for Firefox - Turn websites into applications.
Stylish - A user script manager similar to greasemonkey - read more.

Some popular but not recommended add-ons:
1. NoScript - it is a great extension, but it is too much trouble. If you are visiting a lot of dangerous sites you should use it, otherwise it is better to avoid.
2. Clipmarks and similar - I really fail to see the point in using them. Depending on your needs a personal site (for sharing what your found) or a blog for taking notes will work better.
3. AllInOne Sidebar - I installed it twice. Have no idea why it is consider useful.

Feel free to recommend your favorite extensions in the comments.