Greasemonkey is a super helpful utility Rated 5 out of 5 stars

This is the best EVER add on for firefox allowing you to customize the way that the browser behaves according to your needs and not according to all the unecesary things many sites shove down our browser.

Best scripts are at http://userscripts.org:8080/

This review is for a previous version of the add-on (1.15).  This user has a previous review of this add-on.