Do you listen to Music while surfing the Web?
FoxyTunes lets you control almost any media player and find lyrics, covers, videos, bios and much more with a click right from your browser.
As someone who has 15 different programs open at any given time, this kind of add-on saves me a lot of Alt-Tabs.
9) Domain Details
Displays Server Type, IP/Location Flag, and links to Whois Reports
I frequently use this one to find information on companies via the Web, particularly those who abuse animals, using Whois look-up. It's surprising how much you can find out from a domain registry...
Create free disposable email addresses and paste them directly in forms. This helps to protect you from spam mails and could be useful when subscribing to forums or newsletters.
If you've ever used services like spambox or dodgit, this is for you.
FireFTP is a free, secure, cross-platform FTP client for Mozilla Firefox which provides easy and intuitive access to FTP servers.
If you need to FTP, why not do it right in your browser?
6) Simple Mail
Mail client (POP3/IMAP/SMTP) for Firefox.
I've started using this in place of ThunderBird.
FireShot is a Firefox extension that creates screenshots of web pages.
Unlike other extensions, this plugin provides a set of editing and annotation tools, which let users quickly modify captures and insert text and graphical annotations. Such functionality will be especially useful for web designers, testers and content reviewers.
It's possible to choose whether entire web page or only visible part of this page should be captured.
Screenshots can be uploaded to server, saved to disk (PNG, GIF, JPEG, BMP), copied to clipboard, e-mailed and sent to external editor for further processing.
No more copy and pasting screenshots into an image editor and cropping out all the stuff you don't want.
This extension allows you to use your Gmail Space (4.1 GB and growing) for file storage. It acts as an online drive, so you can upload files from your hard drive and access them from every Internet capable system.
What else are you going to use 4 gigs for?
3) IE Tab
IE Tab - an extension from Taiwan, features: Embedding Internet Explorer in tabs of Mozilla/Firefox.
This one's really useful for sites like NetFlix that, for some silly reason, require that other browser.
2) Adblock Plus
Ever been annoyed by all those ads and banners on the internet that often take longer to download than everything else on the page? Install Adblock Plus now and get rid of them.
It's amazing how different the internet is without banner ads!
1) Web Developer
Adds a menu and a toolbar with various web developer tools.
The most valuable tool for anyone who ever works on Web sites.
Kudos to the developers of each of these add-ons for making them FF 3 compatible so quickly!