Add-ons

User Agent Switcher by chrispederick

The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.

Mozilla Archive Format, with MHT and Faithful Save by Christopher Ottley, Paolo Amadini

— Open web pages saved with Internet Explorer or other browsers (MHT)
— Save many tabs, video and audio reliably, in a single ZIP file (MAFF)
— Return to the original site you saved a page from, and more!

Addons Manager Hilite by custom.firefox.lady

Remembers last selected (hilited) extension/theme/plugin/userstyle in Add-ons Manager. Version 3.0 also includes sorting buttons. Turn off/on the add-on selection list box and/or fine tune behavior via its Options.

Closy by gemal

Provides close all blank/duplicate tabs and Close all tabs to the left/right plus many other options.

Restartless Restart by Erik Vold

This 15KB restartless add-on will add a "File" -> "Restart" menu item and a ctrl/cmd + alt + r hotkey to restart Firefox or Seamonkey.

No More Install Delay by trlkly

UPDATE: XPI delay has been removed in Firefox 40!

Disable the install delay in Firefox. New 2.0 version now includes GreaseMonkey scripts!

Unlike similar addons, this works on Firefox 4 and beyond.

BatchDownload by vlook

Like FlashGet's batch download,but special designed for some image site!

Owl Family Valentine by MaDonna by MaDonna