well im about to leave but here is 1...
http://surfshield.net/
ya those sites are called anonymous surfing.
proxy are used so someone can not trace your connection. say im posting a bunch of pictures of live crops i am growing. and i dont want the feds to be looking in and tracing my picture posts. i will use a proxy to re-route my IP, so im basically using a connection from over seas. its slow as shit, but great for posting illegal shit or somethig along those lines.