These are the Firefox extensions I can’t do without:

Everybody needs…

• CustomizeGoogle lets you turn on Google Suggest by default, adds lots of other links to many types of search results, and more.
• DownThemAll! is a fast replacement for Firefox’s built-in downloader, and lets you quickly download multiple links and images from a page.
• Forecastfox gives you at-a-glance weather.
• Google Toolbar for Firefox lets you check and fix your spelling right within a web page, lets you easily fill in web forms with your personal information, and more.
• SessionSaver remembers what you’re browsing across sessions. It makes crashes tolerable, and you can finally disable that Are you sure you want to close 56 open tabs? message.
• Tab X fixes an egregious UI problem by putting a close box on each tab.

Web developers need…

• IE Tab lets you test your pages with IE’s rendering engine without leaving Firefox
• Web Developer is a deep extension that provides a plethora of tools for manipulating

But where’s…?

• Greasemonkey is interesting, but the whole experience is odd and difficult. I’ll rethink this when Greasemonkey scripts can be installed and updated like Firefox extensions.
• Performancing is a blog editor for Firefox. Its UI resembles a Java app (not good), and it’s missing crucial features like “save as draft”. This looks like it could be promising in the future.