you guys forgot the best ones. the google toolbar for firefox and the ebay negs
SpellCheck
Check your spelling whenever you type in web forms
AutoLink (US only)
Turn street addresses into links to online maps
AutoFill
Automatically fill out forms for faster online shopping
WordTranslator
Translate English words into other languages
http://toolbar.google.com/firefox/
Ebay Negs!
Displays all the Negative Feedback an eBay user has received via right-click or Tools menu. Usage Options 1. "Right click" the mouse on an eBay username on any eBay page, then select Ebay Negs! 2. Highlight an Ebay username link with your mouse on any Ebay page, then "right click" and select Ebay Negs 3. Just "right click" on any Ebay auction page and then select Ebay Negs and the extension will automatically try and work out the username.
https://addons.mozilla.org/extensions/moreinfo.php?id=560
SpellCheck
Check your spelling whenever you type in web forms
AutoLink (US only)
Turn street addresses into links to online maps
AutoFill
Automatically fill out forms for faster online shopping
WordTranslator
Translate English words into other languages
http://toolbar.google.com/firefox/
Ebay Negs!
Displays all the Negative Feedback an eBay user has received via right-click or Tools menu. Usage Options 1. "Right click" the mouse on an eBay username on any eBay page, then select Ebay Negs! 2. Highlight an Ebay username link with your mouse on any Ebay page, then "right click" and select Ebay Negs 3. Just "right click" on any Ebay auction page and then select Ebay Negs and the extension will automatically try and work out the username.
https://addons.mozilla.org/extensions/moreinfo.php?id=560