This will sound a bit strange, but I am looking for a(n) (open source?) program that I saw in a Google search some time ago. I cannot remember, for the life of me, what the site was.
The program does site to site tunneling using various protocols.
It has a client server architecture and allows daisy chaining. It is written/maintained by an Asian author (told you, strange, but that's what I remember about the product!)
It is (I think) open source, and you can download and build the components yourself.
Now, I cannot find this site/program, but am trying to see if anyone else has seen/used it and can post the link to it.
UPDATE (can't post answer in less than 8 hours, so editing the question): By some bizzare luck, I came across the site I was looking for!
The program is called "DeleGate" and can be found at http://www.delegate.org/delegate/. It is a pretty impressive piece of software written by Yutaka Sato.