Quickly Take Down an ASP.NET Web Site

If you need to temporarily take down an ASP.NET (2.0+) web site you can simply add a file called app_offline.htm to the root of the site. The content of the app_offline.htm could contain a message such as "Site currently undergoing maintenance" or similar.

When you add the file to the root, the server unloads the app domain, when the file is remove (or renamed for example) the next request that comes in will restart the app domain, etc...