A while back I wrote an article about web applications that can live wherever you can store a file and not necessarily on a web server out of your control. I probably should have posted a link to Google Group dedicated to unhosted applications, but that's neither here nor there. To recap briefly, what I discussed in the previous article are called unhosted communications applications, like social networking or instant messaging software. This begs a crucial question: Assuming that you're running an unhosted application in your web browser, how do you tell other people how to connect to you with …