The Smithsonian Institute’s National Museum of Natural History has a new and evolving Earth science website at  www.mnh.si.edu/earth (Flash 6 and printable versions).  Currently only the Rocks and Mining section is up and running, but it is instructive at the introductory level.  To come are sections on gemstones, plate tectonics and the Solar System.  There are also downloads and a geogallery.  It is somewhat slow in Flash using a normal dial-up connection., but the printable version has no images.  With a fast connection, this is likely to become a favourite for elementary visualisation of Earth processes.