mod_reproxy for Apache and lighttpd
typester’s mod_reproxy at master - GitHub
Kazuho made mod_reproxy for Apache2 and typester made one for lighttpd.
They add a support for X-Reproxy-URL header, which is used in perlbal often in combination with mogilefs, so your web app can internally redirect static files to other static web server after the authentication etc. is done. It’s more flexible than X-Sendfile since the file doesn’t really have to live on the frontend proxy, which is not often the case in the user uploaded content like photos or videos.
Good stuff.