I heard some time ago about a new method to theme Plone sites. It’s the new Diazo-Theming-Engine that is implemented in Plone now.
I started with a try-out of different free Diazo-Themes (see one in the picture below) yesterday and created a new layout product (project) from scratch for this purpose. I worked on this further today and added some more content to this Plone-AddOn. I have uploaded my current work to github.com (https://github.com/andreasma/am.libocontheme).