(Sample link) NASA for high school students http://www.nasa.gov/audience/forstudents/9-12/features/index.html
(Sample link) National Geographic http://www.nationalgeographic.com
Practice quiz for Earth History from Learnearthscience.com http://www.learnearthscience.com
Yellowstone Supervolcano http://blogcast.wappingersschools.org/groups/cunningham/
History Mural http://www.humboldt.edu/~natmus/lifeThroughTime/Mural.web/MurIndex.htm