ReverseProxy, referring specifically to HTTP(S) servers, is a front-end server 
that passes requests on to one or more backend servers that actually serve the 
content, much as a NAT packet filter with port forwarding. 
In doing so, the server will often implement some kind of load balancing 
among servers that may be just scripts deployed as in RunScriptAsDaemon.


PoundReverseProxy is an excellent tool that accepts HTTPS connections and forwards 
them as HTTP.

Apache can do this too.

- And of course, Squid: www.squid-cache.org
In the still-being-developed branch of Squid, ESI is integrated. ESI is really interesting for high-load sites which deliver a mixture of dynamic and (semi)static content. See www.esi.org

FastCgi and SCGI are variations on this theme that convert the HTTP protocol 
to CGI before passing it on.

Xitami [http://xitami.com/] does this backward in the LRWP module. 
(The backend servers connect to the proxy as clients, rather than the proxy 
connecting to the servers. This results in and increased security risk and 
a drastic reduction in scalability.).....