yxorp is a reverse proxy and application level firewall for the HTTP protocol. It can do all kinds of checks on HTTP traffic, and is highly configurable. It also has other functions that are useful for a web frontend, like load balancing.
kREproxy - kernel reverse proxy server. This is very simple proxy server of http protocol which use simple configuration to deciding where pass the http requests. kREproxy server works in linux kernel spaca as kernel module.