NASA's Earth Observatory provides satellite imagery and scientific information about Earth. The goal is to promote awareness of Earth's climate and environmental change. It's a great resource for educators or for anyone who likes to look at spectacular pictures.
But it's more than just a bunch of pictures. Recent articles written include Vanishing Ice, Escape from the Amazon and Global Garden Gets Greener. They are written for the average Joe. There's even a glossary you can turn on or off. It highlights words in articles and gives the definitions when needed.