That's a great idea. There's a thriving business in those services, but I've always thought the standard payment methods are at odds with privacy minded customers.
Would you consider making your software freely available so anyone could easily set one up? I know for competitive reasons the inclination is to keep it to yourself, but it could get an order of magnitude more use if anyone could give proxy access to their country just by putting the software on a server.
I wonder if there are other kinds of web application servers where we would only have to tack on the payment mechanism to an already existing system?