1. PicLens
PicLens instantly transforms your browser into a full-screen 3D experience for viewing images across the web. Makes browsing through pictures a wonderful experience. The wall and built-in search function, lets you effortlessly drag, click, zoom, and zip your way around a wall of pictures for an amazing viewing experience.

2. Snap Links
You know the times where you have been trying to find something through a search engine, but you have to go through every link one by one in order to find it? All of us have been there, but now with just one click you can open multiple searches with Snap Links. Snap Links allows users to easily open multiple links in new tabs by drawing a box around them.

3. Tab Scope
With Tab Scope you can hover over a tab to get an instant preview of the. The cool thing is you have real time navigation, zoom, and you can even click on links without having to switch tabs.

4. Reminder Fox
This is for those who spend hours on Firefox, including myself. Reminder Fox is an extension that displays and manages to do's. It can set reminders and alert you at the appropriate moment.

5. Download Statusbar
You can view and manage downloads in a small status bar in the corner of the screen, without having that download window get in your way.

6. HyperWords
This add-on makes every word by adding a very handy options menu when you hover over it. Just think, you are viewing a map, and you hover over a location name and you get the option to locate it, search it, or get any information you want on it. Possibilities are endless!

7. Foxmarks Bookmark Synchronizer
If you're like me and use Firefox on multiple computers, you'll want Foxmarks. All you have to do is install Foxmarks on each computer and without you knowing, it will synchronize your bookmarks for you. You can also log onto my.foxmarks.com to have access to your bookmarks where ever you go.

8. Tab Effect
It adds a nice effect to Firefox by simulating a 3D cube being turned when switching through tabs.

9. Cooliris Previews
Cooliris Preview allows you to surf through the web faster by giving you a small preview of the website, without you even having to click on it. Just imagine, surfing without wasting time by clicking on links and coming to realize that it wasn't even close to what you were looking for. All you have to do is just mouse over any link, and the Cooliris preview window immediately appears in order to show you the content.

10. StumbleUpon
This is by far the best add-on out there. It based on your interests, and learns what you like. A fair warning to those that want to download this, it's so great that you will find yourself spending more time than you thought possible surfing around the web. It basically feels like the first time you got high speed internet.

11. Better Gmail 2
Add useful extra features and skins to Gmail, like hierarchical labels, macros, signatures, file attachment icons, and more.

FYI, the "7. Foxmarks Bookmark Synchronizer" has been renamed to XMarks

Besides that, you can try "Personas for Firefox"

Personas are free, easy-to-install “skins” for Firefox that make changing the look of the browser as easy as changing your shirt. With Personas, you can individualize your browser with hundreds of artist-created designs or create your own design to share with a worldwide audience of millions.

That for the web application, wheres Personas are for the Firefox itself... simply install and see...

Thats good to hear... welcome to OpenSource world

Thanks for the invitation. I'm on my way!

Guys,

Another cool Firefox add-on, called as "Cooliris". As it name, Cooliris is simply the fastest and most stunning way to browse photos and videos from the Web or your desktop. Effortlessly scroll a "3D Wall" of your content from Facebook, Google Images, YouTube, Flickr, and hundreds more.

Click here to download