Middleman is a robust proxy server with many features designed to remove
unwanted content, increase privacy, and to simply make surfing the Web a
more pleasant experience.  Some of the highlights of Middleman include
banner and popup blocking, HTTP and FTP content caching, NTLM and Basic
authentication when forwarding through another proxy server, regular
expression substitution in downloaded files and HTTP headers, complete
support for HTTP/1.1 including persistent connections and gzip encoding,
and an intuitive Web interface for configuring the proxy.

WWW: http://sourceforge.net/projects/middle-man/