Security and Privacy Extensions for Firefox
Below are some extensions for Firefox concerning security and privacy.
JS Switch - Add a toolbar button or an option in Tool menu to toggle JavaScript
https://addons.mozilla.org/en-US/firefox/addon/5757
NoScript - Allow active content to run only from sites you trust
https://addons.mozilla.org/en-US/firefox/addon/722
BetterPrivacy - A safeguard which protects from usually not deletable LSO's
https://addons.mozilla.org/en-US/firefox/addon/6623
Web of Trust - Warns you about risky sites that cheat customers, deliver malware or send spam.
https://addons.mozilla.org/en-US/firefox/addon/3456