So in diagnosing the problem below, it would have maybe been helpful to see the IIS logs, At the time I was using the built in web server (for development) that ships with VS 2005. It requires that you address it via localhost, on a port other than what IIS uses. I tried to have a firend hit it using my Dynamic DNS service, and he could not. He could hit my IIS instance on port 80.

Later, I did find you could do this: Go to your web application properties, start options, choose use custom server, and then put the path to your web application in. You'll have to go into IIS and setup a site, or virtual directory for your app.