I don't know that much about VPN, so it could be that this is utterly impossible. Here's hoping, though.

I would like to forward a port from my router to a machine connected to the network via VPN. That way, I could run a simple server on my laptop, and it would continue to work at the same address no matter where I am. The trick is that I don't want people connecting to the server to have to join the VPN. It should be completely transparent to the end-user.

If it's not possible with VPN, is there some other technology that would make this possible? Basically just forwarding a port to a remote machine, one without a static IP.