twhttpd is a powerful secure HTTP proxy.
twhttpd protects your internal Web server by acting as an inbound proxy 
(like a reserve Squid proxy). It can also work as a secure outbound proxy 
to protect your browser client. It allows you to inspect almost every 
detail of the HTTP protocol headers, including the URL request line, the 
server version, user-agent, referrer, cookie, query, etc., in a 
easy-to-use script-like configuration file. 
This program is generally considered an "Expert Tool"; you will need 
knowledge of the HTTP protocol to configure the proxy properly.  

WWW: http://www.geocities.com/samngms/twhttpd/