These are my favorite browser extensions for Firefox (also referred to as plugins by some) that make my life easier (and will make yours too!):

• Tab Mix Plus – I keep so many tabs open at once that if my browser crashes, I would end up spending a lot of time trying to remember everything I was doing / looking at – that is, if I weren’t using this invaluable extension. I used to use the SessionSaver extension, but Tab Mix Plus is more robust and has a richer featureset.
• All-in-One Gestures – Don’t know what mouse gestures are? Wow, you’re missing something cool if that’s the case! Mouse gestures allow you to execute commands within Firefox without using the keyboard, menus or toolbars. Just by making certain movements with your mouse, you can quickly go back a page, close a tab, open a new tab, open a link in a new tab, and more!
• User Agent Switcher – masquerade as Googlebot, Yahoo Slurp, or msnbot or any other user agent to see if a site is doing bot detection
• Web Developer – Great tool if you do any CSS coding or building of web forms, etc.
• Google Toolbar for Firefox – Includes Google Suggest, where you get query suggestions as you type in the search box. Be sure to enable advanced features so you’ll get the PageRank meter. Watch my Google toolbar screencast which will quickly show you how to install, configure, and get the most of of the toolbar.
• SEO-Links – Hover over a link and it quickly checks the top 3 search engines (Google, Yahoo, MSN Search) for link popularity numbers and rankings for the anchor text, displaying the results in a table next to the link. Watch my SEO-Links screencast to see how to get the most out of this handy tool.
• Copy Plain Text – Useful for copying stuff from a web page into Microsoft Word so that the font style isn’t carried over when you don’t want it to.
• ChatZilla – A handy little IRC (Internet Relay Chat) client
• Sage – An RSS feed reader. I actually don’t use this much because my newsreader program of choice, NetNewsWire (for the Mac), is so awesome.
• ViewSourceWith – So that you can view the page source in another program (such as BBEdit for the Mac).
• ShowIP – Displays in the bottom right corner the IP address of the server that’s hosting the page being displayed.
• StumbleUpon – While surfing, get recommendations of related recommended pages to check out from friends and like–minded individuals.
• Search engines for the Search Bar – Technically, this isn’t an actual extension. Up in the top right there’s a built-in “Search Bar” and you can add your own favorite search engines in addition to the default set of engines that already appear there in the drop-down list. The search engines I’ve added include: MSN Search, Wikipedia, LinkedIn, Technorati, and Creative Commons, to name a few.

My most favorite time saving tip isn’t an extension at all. In fact, it not only works in Firefox, it works in IE too, and Safari, and many other browsers. The shortcut is this: Type in just the main part of the domain into the address bar (without the www. in front or the .com at the end) and then hit Ctrl Enter (i.e. hold down the Ctrl key while hitting Enter), then the browser will automatically add the www. and the .com to the address for you! Want more? Then check out the brand spankin’ new Firefox ebook from FirefoxFacts.com. It’s chock full of tips, tricks and hacks to enhance your online experience when surfing with the Firefox web browser. Did I miss any particularly great Firefox extensions? Leave a comment and let me know!