Here are some of the weekly themes of past years:

Earth & Sky Week
Cycles and Recycles Week
Wild Things Week
Legends of the Earth
Unity Week
Exploration Week
Water Worlds Week
Peace Week
Sunrise Week
Exploring the Web Week
Earth Keepers Week
All Species Week
Diversity Week
Adventures in Time & Space
Rainbow Week
Sense of Place
Coming of Corn Week
Thinking Like a Mountain Week