Firefox 3 is good. Firefox 3, plus the right extensions, is great.
Now, a lot of people publish lists of 'best' extensions. It's quick and easy to make these lists. One difference between my list and some of those "99 Must Have, Best Firefox Extensions!" is that is the real list of the extensions that I use every day. These don't just sound good, they work well. These are the extensions that have transformed Firefox for me from just a mere Web browser to an essential part of my electronic office.
To me there are two essential Firefox extensions. I would no more run Firefox without it than I would run Internet Explorer. The first of these is Google's Toolbar for Firefox. This isn't so much a mere extension as it is a bridge to an entire library of useful Web tools I'm not fond of sticking toolbars on my browser. I'd rather have the screen real-estate for the Web site I'm visiting. When it comes to the Google Toolbar, though, it's no brainier. I install Firefox, I install the Google Toolbar. It's that simple.
The Google Toolbar puts Google search where I can get to it whenever I want. For some reason, I prefer the Google Toolbar's upper-left location for the search box on the page to its usual home on the top right. That's nice, but it's not really that big a deal.
What makes Google Toolbar is that I can place the buttons to almost all of Google's Web 2.0 application on it for instant access. For me that means I'm always a click away from Google Mail, Google Calendar and Google Docs.
The next essential extension is Foxmarks. All Foxmarks does is synchronize your bookmarks across how every many computers you have. Doesn't sound like much? To me, with over half-a-dozen computers I use on a daily basis it's a life-saver.
You don't need to be able to keep your house warm in the winter with PCs alone to get value from Foxmarks. Just being able to keep your home and work PCs bookmarks in sync can be invaluable.
While Foxmarks doesn't keep passwords and the like for you, that's a plus as far as I'm concerned. No offense to those services like that will save your passwords for you, but I don't trust them. I'm not going to keep all my security eggs in one out-sourced basket.
There are a few other extensions I use from time to time, but they pale in comparison to this pair. I'm more than willing to learn about other great extensions though, so what extensions do you find aren't just helpful, but essential?