From MozillaZine Knowledge Base

The following browser extensions may be helpful for some users. They are not part of Firefox; you will need to install them separately. If you have a problem with a browser extension, please contact the extension author.

• Mozilla/Firefox Accessibility Extension - View and navigate web content based on structural markup.
• Menu Editor - Hide unused menu items.
• keyconfig - Assign keyboard shortcuts to any command or menu item.
• Mouse Gestures and All-in-One Gestures - Execute common commands by drawing mouse gestures over the current page.
• NextPlease - Assign keyboard shortcuts to jump to next and previous links on search engine results pages and other sites.
• FlashBlock - Prevent Flash content from loading until you click it.
• NoScript - Prevent JavaScript, Java, and other plugins from loading except on domains you choose.
• Tab Mix Plus - Fine-tune tabbed browsing.
• PopupSound - Play a sound when a popup window is blocked.