Galileo U.S.Government.
http://www.jpl.nasa.gov/galileo/
The Jupiter space probe. This is the cutting edge of solar system exploration. The Galileo probe will spend two years of research as it orbits the big planet amongst its moons. Includes regular updates on the probe's progress.

Hubble Space Telescope Space Telescope Science Institute.
http://www.stsci.edu/resources/
A site for all those great high res images of the cosmos. On the wave front of astronomical research, always expect something new and exciting here.

Jet Propulsion Laboratories Web Directory U.S.Government.
http://www.jpl.nasa.gov/
Links to all of the JPL sites. A great place to start if you are looking for info about missions to the planets.

Jupiter U.S.Government.
http://quest.arc.nasa.gov/jupiter.html
General info on Jupiter and the Galileo probe, designed for students from kindergarten to 12th grade. Includes a "teacher's lounge" page with interesting classroom projects.

Mars Pathfinder U.S. Government
http://www.sun.com/mars/default1.html
An Amazing interactive sight with the latest from the red planet.

NASAs hompage U.S.Government.
http://www.nasa.gov/NASA
Just about anything you could want to know about the shuttle or our space program and its various missions. Text, images, sound and animations are online and freely downloadable. It would take weeks of exploring to see half of what is available. The site is a virtual Disneyland of the U.S. space program so pack a lunch and bring the kids.

NASAs Shuttle Page U.S.Government.
http://spaceflight.nasa.gov/home/index.html
The Space Shuttle Missions. This site can get pretty busy but keep trying. Once you get through you'll see why it is so popular. All about the vehicle, the support system, the astronauts, and the special mission reports.

Solar System U.S.Government.
http://pds.jpl.nasa.gov/planets/
Welcome to the planets. This is a wonderful site. Tour the solar system and get some great views of the objects in our neighborhood. A collection of the best images JPL has to offer.