When you perform any Google search, this Firefox add-on brings up a Wikipedia page to the right of your Google matches. With this plugin, I find that Wikipedia provides the answer I want to about half my Google searches. You can get the add-on at GooglePedia Plugin for Firefox

If you are not a Firefox user, you should be. It is an alternative browser to Internet Explorer. It used to be light-years ahead of IE, but then Microsoft borrowed almost all the Firefox advantages and put them into IE 7, so now there's not a great deal of difference for the average user. Stll, Firefox is a bit more user friendly, and it's developed by the Mozilla Foundation, which is a free and open source project, obviously a lot more worthy of your support than the evil empire Microsoft. You can very easily download and start using Firefox by going here. Note that installing Firefox does nothing to your IE installation. You'll be allowed to choose which Browser you want to use as your default, and you can use both Browsers simultaneously.

If you are a Firefox user, but have never used a add-on, get started with this one and then start browsing the add-on site to find all sorts of other tools that will make your Browsing more fun, productive and personal. Some of the add-ons that you can see in use on my Browser in the image above are:
ForecastFox: shows the current and forecast weather conditions in the lower right hand corner
Flagfox: puts the flag of the website's country at the end of the URL in the navigation field
Colorful Tabs: makes the tabs pretty colors
Paypal Plugin: the big blue P to the right of the google search field in the upper right (more about this add-on below)
New Tab Button on Tab Bar: makes it easier to open a new tab (the plus sign to the left of the tabs)
eBay Companion: the little ebay in the middle of the status bar provides a number of tools to make ebay more integrated in your browser

I use many, many other add-ons: these are just the ones that you can see in the image.

The PayPal plugin actually runs on both IE and Firefox and allows you to use "virtual credit cards" to make purchases at any shopping site on the web. The only requirement is that you have a PayPal account. Never again enter your personal credit card information on a web site! This is the only way I buy anything these days! There is one gotcha with this though. If you are buying something online to pick up in a store, or if you are buying movie tickets, or even buying a pizza, sometimes the merchant requires you to show the credit card when you pick up the merchandise. Of couse you won't be able to do this is you use a virtual credit card. If you are buying from a site like that, make sure you read the details to see if you'll need to show the credit card to pick up the merchandise.

Get the PayPal plugin direct from PayPal -- you'll need to log in and then you should see a link to "PayPal Plug-In" on the left under "Tools". The installation is straightforward. Once it's installed, whenever you visit a web page that is asking you for payment information, the PayPal plug-in pops down from the top of your screen -- just click on Generate Secure Card. You are required to log in to your paypal account and then the credit card number is generated and the information automatically fills in on the form below. The purchase is conducted just like any other PayPal purchase. The credit card itself never exists anywhere and you'll never use it again.

FastDial is a Firefox add-on that lets you quickly go to your favorite sites with no typing. As you can see, my FastDial is set up to get me to Yahoo Sports, Pandora, Cox web mail, BookMooch, my blog, mlb.com, Wells Fargo, Netflix, and a bunch of tech reference sites. I have it configured so that when I open a new tab, it automatically displays FastDial and I can just click on the site I want.

The FoxMarks Firefox add-on lets you sync your bookmarks between different computers. If you're like me, you add bookmarks at work and others at home. And, your're constantly getting frustrated because your home bookmarks aren't on your computer at work and vice-versa. FoxMarks solves this problem by automatically syncing your bookmarks whenever you start Firefox. If you add a bookmark at work, the next time you start Firefox at home, the bookmark is there.

The options dialog has options allowing you to make FoxMarks run automatically or only on request, to always synchronize when FireFox is closed, whether to ask for confirmation before synchronizing, whether to log actions, and whether to use your own server to store bookmark information. FoxMarks can also be configured to remember passwords between computers.