Greasemonkey

Download scripts to modify any web page

ArchView

Look inside ZIP, RAR or ISO files before downloading them

Disqus

Blog and webpage comment system

Free YouTube Uploader

Upload several videos to YouTube simultaneously

Faceplus

Express yourself with emoticons on Facebook

BetterSearch

Improve the information offered by Internet search engines

Facebook Toolbar

Integrate Facebook into Firefox

Flagfox

Find out the location of a web server

WordPress

Free CMS for blog and website creation

Hotmail for Thunderbird

Access Hotmail from Thunderbird

Picnik

A photo editor for Firefox

Alfresco

Open source content management system

Metal Lion Vista

Firefox with the graphical interface of Windows Vista

InfoRSS

Keep up with what's going on while you browse

Google Icon

Show the web's icon in Google's results

WordPress.com

The CMS par excellence arrives on the desktop

IncrediMail

Customize your email's appearance and give your friends a surprise

Outlook Connector

Use your Hotmail accounts straight from Outlook

Mail, Calendar, and People

Plan your day and keep in touch

Thunderbird Portable

Use this email manager on any PC with a USB port

Turbo Mailer

Send mass emails

Spark

Complete mail client compatible with different services

Stellar Converter for OST

Convert your Outlook emails to PST format

Microsoft Outlook

Microsoft's email client

Yahoo Mail

Access to your Yahoo email account

Windows Live Mail

Microsoft's multi-account email client

Inky

Receive all your emails in a single client

Zimbra Desktop

Manage all your accounts from the same application

Free Email Extractor

Easily gather email addresses

Mail Bomber

One of the best massive email delivery programs

Mailspring

Mail client to boost user productivity