NASA Kids Club
This site features interactive games and puzzles and rockets, the solar system, space craft and more.  Very appealing for children.

Johnson Space Center Digital Image Collection
Browse through hundreds of photos of previous space missions, organized by platform.

Full Color Space Shuttle Model
Free, printable space shuttle model pattern.

Space Shuttle Glider Model
This is another printable space shuttle model from NASA.

Living and Working on the International Space Station
This is a nice, full color pdf file that can be printed and filed in the child's science notebook.

PBS Space Station
PBS Space Station. includes a photo gallery, interactive quiz, virtual tour, and more..

Space Food and Nutrition
An Educator's Guide With Activities in Science and Mathematics.  Food related projects for all ages.

Building the International Space Station
All about the International Space Station.

Your Weight on Other Worlds
Figure out how much you would weigh on other planets. 

Animal Astronauts
Information about animals that have traveled in space.

How to Become an Astronaut
Everything you'd ever want to know about becoming an astronaut - straight from NASA.

Astronauts:  Space Explorers
This is a nice summary page by Enchanted Learning.  Short, concise biographies on a number of prominent astronauts.