MyBB Community Forums

I just wanted to know if there is a plugin for a theme demo site.

Example : 

Except I want it to allow theme Switching and on all available themes.

If there is a plugin that already exists please inform me due to the fact Ive been trying to find one for over 2 days now.

We're running something similar at http://mybbdesign.com/demo/ to demonstrate different themes. It does not cover backend interface though.