a pat on the back for that mango... nice one indeed
here is another i would recommend a php proxy addon... install and.. at the bottom toolbar you will see a P right click options and update list and you can add them to it your self
so say you google and you dont want to use google cache to view the site...etc... just right click and select open by phproxy and surf anon no adds

/https://addons.mozilla.org/en-US/firefox/addon/3239
your addon works fine here is my header from shields up
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Connection: keep-alive
Host: www.grc.com
Referer: http://www.grc.com/x/ne.dll?rh1dkyd2
User-Agent: ELinks (0.4pre5; Linux 2.6.10-ac7 i686; 80x33)
Cookie: temp=ngserfno4xxx; perm=dy0pdsxf4
Content-Length: 32
Content-Type: application/x-www-form-urlencoded
Accept-Charset: ISO-8859-1;q=0.7,*;q=0.7
Keep-Alive: 300
FirstParty: https://www.grc.com
ThirdParty: https://www.grctech.com
Secure: https://www.grc.com
Nonsecure: http://www.grc.com
Session: dqkylmb23h
User-Agent: ELinks (0.4pre5; Linux 2.6.10-ac7 i686; 80x33)