Firefox is the browser I use both at home and at work. I am using version 220.127.116.11 and have only encountered one problem (a corrupt install of the ForecastFox extension) with Firefox to-date. The following list is an update of extensions I have installed:
All-In-One Sidebar - This one was recently installed based Ed Bott's list of favorite Firefox Extensions. It lets you view bookmarks, downloads, extensions, and more in a sidebar tab. This extension has improved over time. It's a good way of bundling various windows, options and extensions in one place.
Autofill - Automatically fill out HTML forms or automatically highlight fields that can be filled out by Autofill. I don't use this very often it seems, so I may be ditching this soon.
Bookmark Backup - Create a backup of your bookmarks and more each time you exit Firefox. Version 4 now includes the option to create a backup at regular intervals.
BugMeNot - Get sick and tired of all those "free" news sites that require you to be a registered user? With BugMeNot you can retrieve a user name and password from public database at bugmenot.com. If you have the Autofill extension installed, BugMeNot will automatically fill in the user name and password. A warning: several news sites regularly check bugmenot.com for 'rogue' accounts and delete the accounts. I have noticed that more sites are dropping the requirement to register in order to access free information. This is another extension that sees little use lately.
Forecastfox - Want to know current and future weather conditions? Then this is the extension for you. Totally configurable, you can put the weather in a toolbar, sidebar or status bar, choose which variables to display and for what cities. Weather information from Accuweather. Indispensible. Numerous improvements over the past few months including the ability to change measurement units for specific weather variables.
FoxyTunes - Lets you control your favorite media player without having to leave Firefox.
Greasemonkey - A User Script Manager that lets you add "bits of DHTML" to web pages. You can find hundreds of scripts at Userscripts.org or you can write your own. I use Linkify Plus (create links out of URLs), Secure-em-all (redirect to secure sites - useful for logging into sites), Bloglines sidebar tweaker (minimize/squeeze the Bloglines sidebar to show as many entries as possible) and Gmail Smart-Delete Button (add more functionality to the new Delete button)
IE View - For sites that require IE, you can right-click on a link or on the page itself and open the URL in an IE window. You can also add pages to the "Always-in-IE sites" listing and Firefox will automatically open that page in IE.
Tab X - Add a small close button to each tab and remove the close button from the end of the tab bar.
Extensions I used in the past:
Sage - I recently started using Bloglines to access my feeds, mainly because I could access them from any computer (at home and at work). Sage is a very compact feed reader. I you only use one computer to access the net, I highly recommend it.
del.icio.us - Integrates Firefox with del.icio.us, the social bookmarks manager. A quick way to add pages to My del.icio.us bookmarks. Integrates into All-In-One Sidebar. The hype about this website outweighs it's usefulness. I rarely use the site. If your into the whole "social networking" thing and are looking for new sites to browse, then del.icio.us may be the place for you.