The United States Geological Survey, the principal source of Scientific and technical expertise within the Federal Government, sponsors this e-mail service for anyone with general Earth Science question. Offers links to USGS recommended sites. A comprehensive resource of environmental information.
Viewers can browse the Map Machine or take off on an expediation.
Also, the Visualization Project presents scientific information about our planet through images and long-range forecasts based on computer models. Contains geological information including comprehensive lists of largest quakes. Explains plate techtonics, and the different scales seismologists use to measure tremors. Updated at least every week, this page is an excellent reference for reports, projects, or just shear fun.