1: Manage Multiple Identities on the Web Without Logging Off

Most websites use Cookies to store your login information and you can have just one cookie per website per web browser but with CookieSwap, you can maintain multiple cookie profile and switch between them in a click.

2: Let Firefox Turn Off The Computer When All Files Have Downloaded

Turn off the computer automatically as soon as Firefox has downloaded all the pending files in the queue.

3: Firefox Extensions for Offline Browsing, Blogging

4: When Its Time to Work, Shut Down Websites That Distract You

This is like a self-imposed restriction to help you concentrate on work.

5: Install WordPress Plugins and Themes from Firefox, No FTP

OneClick Firefox Extension allows you to install (or update) new WordPress themes and plugins via Firefox.

6: Avoid Office Embarrassments; Stop Web pages from Autoplaying Music or Videos

Music and Videos that autoplay in the browser is not that big an issue if you keep your speakers muted or use the headphones, but it can be very embarrassing in all other cases.

7: Read Full Articles on The Wall Street Journal Without a Subscription

Add the text mod=googlenews_wsj to URL immediately following the .html filename.

8: Download Sparky: The Official Alexa Toolbar for Firefox

Right click the traffic graph in the status bar to quickly access the Alexa Detail pages, Cached Pages, Search Pages and more.

9: Combine PDF Files, Convert Web Page URLs to PDFs on the fly

LOOP is a unique extension for Firefox that converts the web browser into a proper PDF writer that can do some amazing things sometime not possible in other free PDF conversion software.

10: Use Notepad, Vim or Any Text Editor with Firefox for Writing Text

Geeks may configure Firefox with Vi or Emacs.

11: A Single Desktop Upload Tool for YouTube, Flickr, Picasa and more

Fire Universal Uploader is a Firefox extension that lets you upload and also download videos, pictures, documents and other files to the above websites from a common interface.

12: Remove Unwanted Clutter from Firefox Right-Click Menu

Menu Editor lets you rearrange (move) existing menu-items, group similar commands or remove items that you rarely use.

13: Know What Your Favorite Blogs Have Written About a Web Page

The BlogRovR extension is so good that Mozilla guys have made it an officially recommended Firefox extension.

14: Save Web Pictures with Firefox in Different Folders Automatically

This extension helps you to quickly save images into different folders without having to click through your folder structure again and again.

15: Recognize Websites in Google Search Results Quickly

To automatically add these favicons to Google search results,just grab either the CustomizeGoogle or Google Icon extension from the Mozilla add-ons website.

Google Custom Search