Imagine that all the looks from all plone skins made was available to you and that you could choose different parts from different skins. This is the idea behind SubSkins. Hopefully, a lot of skins will be devided into smaller css-files, which can be added to SubSkins and be selected from a control panel. The plan is also to have several "color schemes" so one can chance the colors in the same way. This way it would be possible to customize the look extensively without knowing any css.