One common FB business model is to first create a free, hopefully popular Facebook application. Once you have an audience or a substantial userbase, you direct

One common FB business model is to first create a free, hopefully popular Facebook application. Once you have an audience or a substantial userbase, you direct those users to a more powerful version of the application on your own website - specifically, a paid version. In other words you use facebook to build popularity then redirect that popularity to a more traditional paid web app.