11 Powerful Firefox 3 Add-ons... Plus more

Some really awesome extensions listed from this blog

11 Powerful Firefox 3 Add-ons That Can Replace Standalone Applications

I would like to honor this list by adding a couple more extensions.

DownThemAll DownThemAll (or just dTa) is a powerful yet easy-to-use Mozilla Firefox extension that adds new advanced download capabilities to your browser. Replaces external download managers.

ScrapBook is a Firefox extension, which helps you to save Web pages and manage the collection. Replaces offline web browsers.

Adblock Plus Blocks advertisements. Replaces ad blockers.

LinkChecker Check the validity of links on any webpage. Replaces link validaters.

FoxTorrent Download torrents right in Firefox! Replaces bittorrent clients.

Plain Old Webserver Turn the web on its head with the Plain Old Webserver (POW), which adds a server to your browser. Replaces external web servers.

IE Tab Embedding Internet Explorer in tabs of Mozilla/Firefox. Replaces opening Internet Explorer.

Honorable mentions:

MeasureIt Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.

ColorZilla Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.

Sameplace Talk with your contacts from GMail, Jabber, Twitter, MSN, Yahoo!, ICQ, AIM. Replaces Instant Messengers.