Image Zoom – This is one of my favorite extensions and its functionality seems so basic, it should have been with browsers from the start. Install this add-on and you can simply hold down right-click on an image and then use the scroll wheel to zoom in or zoom out images. Great for getting things out of your way or seeing closer up detail within the browser.
AdBlock Plus – I don’t know if I can go back to the internet without this extension. Basically most ads are already blocked without intervention thanks to a subscription (free) list that keeps it updated on popular ads to block. No more banner ads or annoying flash popping up promising a free iPod or Wii or whatever is the latest gadget. It still maintains the ability to add custom images or iframes to block. Save your bandwidth, let pages load faster, and get to the content of pages you’re looking at.
Tab Mix Plus – Tab Mix Plus adds a lot of features that just allows tab-based browsers to flex their muscles. I use TMP primarily to save my session at the end of Firefox. I can close the browser where ever I am. It will open whatever windows and tabs I had open every time I re-open Firefox. It also allows you to open closed tabs by middle-clicking any blank spot on the tab bar. You can also clone a tab over to a new tab with just a keyboard shortcut.
FoxMarks – Create a backup of your bookmarks and keep them synchronized on their server. You need this extension if you have more than one computer. Keep your bookmarks in sync between your laptop and your desktop or any other configuration. Access your bookmarks from work easily by visiting their site and view your password-protected bookmark or even create a separate profile for your home bookmarks.
IE Tab – Some things IE still does better, like ActiveX or some media that causes Firefox to freak out. You can right-click links and tell them to open in an IE tab or have it start up IE and load the page there. It’s good for testing out pages as a webmaster or getting around problematic pages that aren’t rendering properly for your favorite browser.
DownThemAll – Find a page full of clip art that you want or a list of files that you need but don’t want to click every single one to download them? With DownThemAll, you just launch the extension and it will look at the page and offer to download all the files. You can uncheck files you don’t want or use a filter to just grab those that you do want, like *.jpg or minutes*.doc. It’s a convenience when you need it and completely out of the way when you don’t.
Download Statusbar – This is really an extension that is going to depend upon your preferences. The default download window of Firefox just really annoyed me because it was getting in the way or hiding itself all the time. This extension puts the download info in the otherwise useless space of the status bar. It doesn’t sacrifice any information in squeezing into that small space and it makes downloading a much more seamless process.