DeleGate: Multiprotocol proxy/plumbing-tool/converter [TCP,SSL,HTTP,NNTP,DNS…] (delegate.org)

There have been several HN posts about useful "plumbing" commands to tunnel things through networks (netcat, socat, ssh-tunnels, ...). DeleGate not only can proxy simple byte streams through the network but also convert between a diverse set of application-protocols. While I wouldn't advertise it as a production server it makes it extremely useful if you have to proxy yourself out of a limited network.

The link goes to the examples-page, the main page is of course reachable at http://www.delegate.org/.