As performance reasserts its prominence and features become less of the driving force behind browsers, I find myself looking at the list of inactive extensions in Firefox with jaundiced eyes. It's been months since I've added a new extension, but the ones I still have I use regularly, and several are actually new to me for this year.
Part of the problem with add-ons is that they're such a personal, subjective thing. What do you need? Why do you need it? One of my favorites is a minor, tiny thing, but it saves me so much time that I have trouble when I use browsers without it. Dragdropupload gives you the ability to drag a file from your desktop into any text field in a Web page. Lightweight but extremely effective, if you e-mail a lot of attachments, this should quickly become a massive time saver.
I use it at work to drag images into form fields that then upload them to the CNET servers. Instead of having to navigate that obnoxious folder tree, I just drag the file and drop it into the appropriate field.
One of the problems with Dragdropupload is that sometimes Firefox updates break it, and it takes me a while to bring it back to life. There are two user-end solutions to solve that conundrum, but both are somewhat risky. Using either Nightly Tester Tools or MR Tech Toolkit, you can use the override compatibility feature to force Firefox to recognize outdated extensions. However, as I've noted before, this greatly increases the chance of having Firefox crash on you.
I wouldn't recommend doing this unless you can't find the same feature replicated elsewhere. I used to force compatibility with AutoCopy, another tiny little extension that introduces Linux-style compatibility to Firefox. Since I do a lot of cutting and pasting, AutoCopy and its multiple clipboards and automatic functionality make it a must-have for me. The mileage you can get out of it may vary with use, of course.
I have one frivolous extension installed: Cooliris. For compatible Web sites such as Flickr, YouTube, and Amazon, it introduces a bit of a futuristic vibe to browsing the Web. Your display turns into a full-screen wall of images, smoothly zooming in and out. It makes me wish that we all had Minority Report-style interfaces to work from instead of these comparatively-clunky mice.
The last new-to-me add-on that I still use is Session Manager. Besides resurrecting crashed browsing sessions, it also lets you save current ones and keep them for later. You can configure how the sessions are named, change the default saved-sessions' location, encrypt saved-session data, and configure how post data gets saved, even from encrypted Web sites. Since each session file created by Firefox includes text data, cookies, and history, as well as tabs, being able to recreate all that information effortlessly is incredibly helpful and shouldn't be underestimated.
If you've got an extension that you've discovered in the past year and can't imagine how you got by without it, tell me in the comments below.