http://www.ghacks.net/2009/02/12/firefox-55-add-ons-to-increase-your-security-and-privacy/
The following list will contain Firefox add-ons that protect the user from various threats on the
Internet. They have been divided into the categories Browsing, Cache, Cookies,Identity & Privacy, Passwords and Misc. Each link will lead to the Mozilla homepage that contains additional information and download possibilities.
All but one add-on should be compatible with the latest
version of Firefox 3. Some of them are experimental add-ons that require an account at the Mozilla website before they can be downloaded and installed.
FlashBlock - Blocks all Macromedia Flash content from being loaded. can turn on & off.
NoScript - Disables scripts automatically on the Internet with the option to enable them
individually. very good to get don't fit flash block with this it dose help to stop Flash.