I want to host multiple web sites (all with different domains - not sub domains) with the same ASP.NET MVC app. I need the app to act differently based off the domain, but
This should be possible with IIS using the host headers field in the bindings settings. You can add as many different host headers as you want for your application. And as long as that domain somehow goes to that host on that particular port (http or https or custom), then that application will be used.