CMS: Style Changer

I didn't know which thread to put this one under (Power CMS, CSS, PHP...)

I would like to find a solution that will allow registered users to be able to change the look of their pages on the back-end or admin section. Whether it is choosing a whole template or style sheet to change the look and feel of their pages. I was hoping that there would be a 'server-side' solution (mysql/php) rather than a client-side using cookies and javascript. Word Press and Joomla has their template and theme solutions and was wondering if WA will come up with a similar solution to add to their dreamweaver extensions. I am not a big PHP hard-coder but I do understand most of it.