Wind, Water, Fire, and Earth. Those are the main elements of nature. With the elements theme, it is bring those elements to you in the form of top-to bottom themes.
There needs to be four palletes, one for each element.
Water should focus on the cool blues, maybe a blubuntu pallete.
Fire needs Red-Black.
Wind needs cool greens-white.
Earth needs a natural feel to it, maybe the same shades that Ubuntu have now.
Post here some images that could help people to develop ideas.