Well the google proxy shows the webpage as it is seen from a cell phone.
Also good results if you use httProxy add-on for Flock, see http://www.pcmesh.com.nyud.net:8080/ip-check.cgi
A lot of webproxies give the originating IP via HTTP_X_FORWARDED_FOR, they do not show generall HTTP_REFERER. For HTTP_USER_AGENT you can use User Agent add-on to use Internet Explorer, Opera or Netscape (well it is faked), Then also REMORE_ADDR, REMOTE_HOST, REMOTE_USER should be anonymous.
Because some run $_SERVER['HTTP_X_FORWARDED_FOR] or $_SERVER['REMOTE_ADDR]
But the chained proxies are best, and have NoScript enables, because all these webproxies log through urchin.js etc.
Hello Polonus!
As for a chained annonimiti servise i like to use JAP see here: http://anon.inf.tu-dresden.de/index_en.html , but I can’t figure out how to set it to work correctly with avast! WebShield. maybe you can look at it & say your IT security “guru” word