earthquake.usgs.gov - The National Earthquake Information Center, the national data center and archive for earthquake information, is an invaluable resource for those interested in geologic history and seismic phenomena.

www.desertusa.com/life.html - A great site dedicated to the environment, ecology, and culture of the deserts of the American Southwest.

heritage.stsci.edu - The Hubble Heritage Project offers images beamed from the Hubble Space Telescope, with new images added on the first Thursday of each month.

www.earthsky.com - The producers of a daily radio show covering Earth, space, and environmental science offer their current and archived shows.

www.geology.wisc.edu/~jill - The University of Wisconsin-Madison's department of geology & geophysics has gone online, offering access to faculty research, lectures, and images from their geology museum.