National Environmental Education Week is next week, April 15-21, 2012, right before Earth Day. The site for it has some great resources for teachers, including lesson ideas and resources.
One resource that I like is an infographic entitled "STEM and Our Planet" that has information, data, and resources for relating STEM Topics to the Environment.
The infographic and the site are great ways to incorporate Environmental issues and science into STEM topics.
STEM Resources for Educators and Students
Great Earth Day Resources for Educators
Glogster Earth Day Contest - great education project with prizes