Mozilla Firefox by itself is already a great program, providing great security, a intuitive tabbed-interface that manages many windows easily, and other conveniences—all for free. But what makes the browser better than its competitors are its extensions. Extensions, or Firefox’s plug-ins, either improve an existing feature, or provide entirely new functionality. Here’s a list of extensions I use:

• DownThemAll! – A built-in download manager that lets you download two or more links on a page at the same time
• Duplicate Tab — Provides duplicate tab functionality
• McAfee SiteAdvisor Firefox Extension – Warns you about potential malware—before you go the website in question
• Tabbrowser Preferences – Allows more detailed customization of the tabbed interface’s behavior
• VideoDownloader – Use this to save a copy of embedded videos, such as YouTube and Google Video, on your computer
• Wizz RSS News Reader – A simple yet powerful RSS reader

You can download these extensions and others from the Firefox Add-ons website.