Add-ons

FlashGot Mass Downloader by Giorgio Maone

Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.

Speed Dial by Josep del Rio

Direct access to your most visited websites

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!

AutoCopy by Autocopy, Michael Lidman

Select text and it's automatically copied to the clipboard. Also pastes on middle click.

AutoPager by Wind Li

AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.

MR Tech Toolkit by mrtech

(Formerly Local Install) The primary goal of this extension is to provide the tools needed to install and manage extensions and themes locally and tons of other features.

Note: With Toolkit 6.0 Auto Archiving is fully working in Firefox 2.0 and temp...

Update Notifier by Todd Long

Note from Mozilla: This add-on has been discontinued. Try Add-on Update Checker instead.

Notifies you when updates are available for your extensions and themes.

Collector's Note Automatically install updates and restart Firefox, gets rid of annoting "Install Updates" and "Restart Firefox" windows on startup.