Firefox add-on

This has to be one of my favorite add-ons for firefox it's call Stylish.
Stylish add-on link
Then with Stylish installed use a theme from http://userstyles.org/ you can change the look of how you view sites.

The reason why I like it so much is with the right theme it's so much more pleasant on my eyes to view web sites, No more harsh white backgrounds or generally painfully bright sites for me.

Firefox Add-on: PDF Download

Firefox add-on PDF download allows you control the behavior of Firefox in four different ways:

1. Download the PDF file.
2. Open the PDF file.
3. View the PDF file as HTML
4. Bypass PDF download

Download Firefox add-on PDF Download

KeyScrambler Personal

One of the biggest dangers you face online is theft of your user name and passwords for logging into commercial Web sites (such as banking and financial sites) and Web-based e-mail accounts. A criminal who steals that information could empty your bank account and use your e-mail address to pose as you.

This add-in to Internet Explorer and Firefox promises a simple way to keep you safe. As you type your password, KeyScrambler Personal scrambles it so that the information sent out over the Internet doesn't match what you type. That way, a lurking crook won't be able to steal your private information.

A small icon sits at the bottom of your screen, telling you that KeyScramber Personal is going about its work. As you type, you'll also see the scrambled text that the program is sending.

KeyScrambler

Mozilla Firefox, Portable Edition

Mozilla Firefox is a fast, full-featured web browser that's easy to use. It has lots of great features including popup-blocking, tabbed-browsing, integrated search, improved privacy features, automatic updating and more. Plus, thanks to the PortableApps.com launcher bundled in the Mozilla Firefox, Portable Edition, it leaves no personal information behind on the machine you run it on, so you can take your favorite browser along with all your favorite bookmarks and extensions with you wherever you go.

Go here

Mozilla Firefox

The award-winning Web browser is better than ever. Browse the Web with confidence. Firefox protects you from viruses, spyware and pop-ups. 
Enjoy improvements to performance, ease of use and privacy. It's easy to import your favorites and settings and get started. 

The latest version delivers easier navigation for everyone, including those who are visually or motor-impaired. Firefox is the first browser to support DHTML accessibility, which, when enabled by Web authors, allows rich Web applications to be read aloud. Users may navigate with keystrokes rather than mouse clicks, reducing the tabbing required to navigate documents such as spreadsheets. Firefox is also the first browser to meet US federal government requirements that software be easily accessible to users with physical impairments.

Firefox homepage

MozBackup

This is a very useful program allows you to back up Firefox, Thunderbird, and other Mozilla products..
MozBackup is a simple utility for creating backups of Mozilla Firefox, Mozilla Thunderbird.
It allows you to backup and restore bookmarks, mail, contacts, history, extensions, cache etc.