XSS Guardian 0.1
Firefox addon that block XSS from grabbing any cookie.
XSS Guardian controls every url you visit, and block url with malicious XSS code. Just a click to the icon disables XSS Guardian's function. XSS Guardian (now) controls only XSS via GET vars.
The XSS Guardian extension allows you to check any URL that searches the Cross Site Scripting used for cookie grabbing, and blocks it.
Note: The XSS Guardian addon is cross-platform and it works on Mac OS X, Windows and Linux.