Giorgio Maone, the author of the NoScript Firefox plugin has recently been posting to the boards about a new experimental version of the plugin that intends to protect against XSS. The concept of the tool change is to detect when one site is attempting to send you to another site with XSS within the query string. Obviously there are more ways to XSS sites than the query string, so this mostly relates to certain forms of reflected XSS.
Giorgio is open to comments, so I would recommend that anyone interested in testing out the tool download it and give their feedback. Thus far there are a number of bugs, since it is very restrictive in what it attempts to stop, but being experimental there is lots of room for comments and improvements where they make sense. A big thanks to Giorgio for taking the time to let us all test his code. I, for one, have got a lot more testing to do!