Over the last 2-months, ive been really getting into Firefox, ive found some quite useful extensions and scripts that extend the browser to my specific needs. For the hardcore browsers out there, download in the following order:
Firefox 1.5
The latest version of Firefox released in November 2005.
http://www.mozilla.com/firefox/
Google Toolbar for Firefox
The best way to surf and browse the internet.
http://toolbar.google.com/firefox/
Google Blogger Web comment for Firefox
A dynamic list of wesbites/comments that people have made about the current page that you are browsing. http://www.google.com/tools/firefox/webcomments/index.html
Tabs Session Saver
Re-opens previously running tabs before your browser was shut/closed.
https://addons.mozilla.org/extensions/moreinfo.php?id=436&application=firefox
Tabs Mix Plus
Provide a much detailed control of tab behaviour, a must for hardcore surfers.
https://addons.mozilla.org/extensions/moreinfo.php?id=1122&application=firefox
del.icio.us Toolbar for Firefox
A great way of tagging and bookmarking your favourite sites from any machine
(A pity that Yahoo have bought them)
http://addons.mozilla.org/extensions/moreinfo.php?id=1532
Greasemonkey Script Manager
A javascript engine which enables developers to write simple scripts to manipulate your web pages.
https://addons.mozilla.org/extensions/moreinfo.php?application=firefox&category=Popular&numpg=10&id=748
Greasmonkey script(s)
Hundreds and hundreds of user developed Javascript plugins for Greasemonkey.
http://userscripts.org/
Update:
One other one to keep an eye out for is AllPeers, its a file sharing extension which uses one of the Peer Networks (possibly BitTorrent) -- its not available yet.
http://www.allpeers.com/more_f.htm