Here is a list of the Firefox plugins I am using:
Alexa Sparky

Sparky is Alexa Internet’s free Firefox status bar plugin. Sparky accompanies you as you surf, providing you with Alexa data about the sites you visit without interrupting your browsing.

Discover website traffic trends — Is this site getting more popular, or less?

Get detailed traffic information including Reach and Rank — How does this site’s traffic compare to other sites on the Web?

Surf more efficiently with Related Links for each page — If I like this site, are there others that I might want to visit?

Gracefully navigate past dead end error pages — Enable Sparky’s optional custom error handling to get relevant alternative links when your browser encounters a network error.

Download Statusbar

View and manage downloads from a tidy statusbar – without the download window getting in the way of your web browsing.

Firebug

Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page…

Firefox sync

Free browser add-on that lets you stay in sync with your Firefox. Access your history, passwords, bookmarks and even open tabs across all your devices.

Flagfox

Displays a country flag depicting the location of the current website’s server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more…

Screengrab

Screengrab! saves webpages as images…

It will capture what you can see in the window, the entire page, just a selection, a particular frame… basically it saves webpages as images – either to a file, or to the clipboard. It captures Flash too!

Server Spy

Server Spy indicates what brand of HTTP server (e.g. Apache, IIS, etc.) runs on the visited sites.

Showip

Show the IP address(es) of the current page in the status bar. It also allows querying custom information services by IP (right mouse button) and hostname (left mouse button), like whois, netcraft.

Yslow

YSlow analyzes web pages and why they’re slow based on Yahoo!’s rules for high performance web sites.