Firefox Extensions: Which Are the Best and How to Make Your Own
Mozilla Firefox has been cutting into Internet Explorer’s market for years. Some of the best features of Firefox are the extensions you can add on yourself. Here’s a look at what’s available and how to build your own Firefox extensions.
Here are a few:

Unless you use Internet Explorer. In which case, stop now! Please.

Adblock Plus (Must have)

This is the first extension I always add to Firefox whenever I install it. Adblock Plus removes unwanted content, such as ads or flash, from a Web page based on a set of user-defined filters. A companion to Adblock Plus, Adblock Filterset.G Updater, automatically downloads the latest version of a set of filters that will block most ads on the Web.

Greasemonkey

Greasemonkey is a Firefox extension that allows you to modify Web sites to improve functionality or appearance. This extension associates a bit of code with specific Web pages. This code runs every time you visit the page, dynamically changing the appearance and functionality of a page. In many ways, these scripts are just Firefox extensions in a different format.

All-in-One Sidebar

The All-in-One Sidebar extension adds a sidebar panel to the browser, allowing you to quickly switch between windows, such as the downloads, extensions, or theme windows. Inspired by the Opera sidebar, this extension includes a toolbar that can be customized.

Download Statusbar

You’re probably familiar with that sometimes-pesky “Downloads” window that pops up whenever you download a file in Firefox. Download Statusbar prevents that window from popping up and instead provides you the same information in the status bar at the bottom of the browser window. (You can still manually open the “Downloads” window if you find you need it.)

SpellBound

SpellBound provides a spell checker similar to the type used in a word processor. As a word is entered in any text box on the page, Spellbound highlights the misspelled words with a red dotted underline. The spelling can then be easily corrected by clicking on the red underlined word, and Spellbound will pop up a menu with potential corrections, providing a choice of which word to replace.

PDF Download

The PDF Download extension allows you to choose how to handle PDF (Adobe Acrobat) files. Every time a PDF link is clicked, this extension offers the choice of whether to open the PDF file inside a new tab, download it to the computer, or view it as HTML.

FoxyTunes

Foxy Tunes places controls for the media player of your choice within the Firefox toolbar. You can pause, forward/reverse, play, adjust the volume, and view what is playing. Almost all major media players are supported. You can find a number of FoxyTunes skins here.

Download Them All

Download Them All will download, in just one click, all the links or images contained in a Web page through a set of customizable filters.