How to create a live preview for sites?

Hi Everyone!

Does anyone know how to create a live preview site like the kind you see on Template Monster and other template sites. I have some site templates that I'd like to post and I would like for people to be able to preview the live site. Does anyone have any ideas on how to do this?:)

You could just create another version of the sites, like demo version where you can't click the links, or whatever you want.

Then make header like on Template Monster saying like: 'This is a live preview, get sites <here>'.

My head tells me to do it like this, but there might be a cool codes to it too.
If you don't wanna do it this way, you should wait for more replies
~Peace