Hi, if this is not the place, remove it, but i wish to share my new plugin recently uploaded, here:http://wordpress.org/extend/plugins/development-theme/
It´s very easy, just two options and let you use one theme while logged as admin, and other theme for rest of users or visitors. Or you can use it as a “comming soon” alternative theme while working on the next release, or to put your site “under maintenance” with some alternative theme or you can do what you want with it, in fact.
What you think? Thanks.