Comet Hale-Bop photographed by Brandon Nuttall
Science-Education Gateway. More than 20 lesson plans for grades K-12 developed through the University of California-Berkeley including Auroras: Paintings in the Sky, Best of the Solar System, The Comets Tale, Classifying Galaxies, Electromagnetic Radiation on Trial, Exploring the Planets On Line, The Extreme Ultraviolet Explorer, Eyes in the Sky, Find That Comet, and more.
Windows to the Universe, University of Michigan. Contains excellent views and description of the solar system and its planets. It has online information, movies, animation, and data sets about the solar system as well as the universe and physical sciences.
Atlas of the Universe.
Astronomy Cafe, by Dr. Sten Odenwald. Contains lots of information about the stars and planets. Also has an "Ask the Astronomer" section.
Abrams Planetarium. Has lots of information and links to very useful sites. Has a very good monthly skychart that can be printed.