University of Guelph
Canada's Polar Environments
This site is a set of images along with volumes of information make this site a treasure trove. The site has satellite images.
American Institute of Biological Sciences
Action Bioscience: Issues in Environment
This site from American Institute of Biological Sciences provides a collection of articles on current issues in environmental science and human impacts on the environment. Several articles available in Spanish.
PBS
Nh Pbs: Nature Works: Ecosystems
How would you define an ecosystem? Check out this educational resource to learn more about the living and nonliving parts of different ecosystems.