I've been working with the Weaver theme for WordPress for several years now, and have been selling some of the designs I've made for it.
Weaver is a free theme, and has an interface that allows anyone to easily change the look of their site.
If you use Weaver II, Aspen, or Weaver Xtreme, I have written a conversion plugin for the theme settings.
Here are the latest designs. Click through to the product pages to see the details.