Hi i new here and are testing this great forum script out. I did see in the demo a skin called Extra Mini, is this skin public or are it just for the demo since i would really love it for my site.

Hi there, everything you see on miniBB websites, is for public. Even if it's not for public download, you could get it from the website, checking the source of the webpage.

Check for miniBB skins and more on this topic, in the special thread. From there you'll be also able to download Extra Mini skin.

Heh, you can even download the newest minibb skin and templates which are not yet released, from these forums :)
There's no secret at all...