>>Let's say I wanted to allow bidirectional communication between an internet client and a host computer behind a router without having to configure port-forwarding on the router. What are the options to accomplish something like this?
>
>So I found this very cool tool that does exactly this:
>
>https://pagekite.net/
>
>The fast, reliable way to make localhost part of the Web.
>PageKite makes local websites or SSH servers publicly accessible in mere seconds, and works with any computer and any Internet connection.
>It's also 100% Open Source.

And here's another one:

http://www.ultidev.com/products/HttpVPN/