Rated 4 out of 5 stars
I used to use this all the time but it's super broken in Firefox 4. After trying to figure out the easy way what was causing the "Error: Permission denied to access property 'host'" error that I kept getting (especially on Facebook), I finally had to go through, disable everything, and enable one by one. It eventually lead me to this extension causing it all. FYI to anyone using Firefox 4.
On the other hand, on his website there is a link to install for Greasemonkey. Oddly enough, THIS has no problems at all working. Weird.
Please check with latest beta of Firefox 4
I would really appreciate if you can check for this possible bug with latest beta of Firefox 4 (beta 12). I hope that this issue is over now. You can mail me your feedback to firstname.lastname@example.org