This package kicks out and prevents any Umbraco users from entering the back office - usefull for when the administrator wants to perform some kind of upadate to the server / database.
A querystring override is provided (and can be changed) to allow the administrator to enter the system via a "back door".
The administrator can also provide a "node id" to an Umbraco managed page to allow a usefull error message to be shown to the user after being kicked out (or if they try to access the login page).
Project is currently in beta so let me know (or contribute) if you have any ideas / bugs.