Children's Television Workshop - CTW Family Corner, a test site featuring parenting information and Sesame Street activities for kids.
The Learning Studio of the Exploritorium - Online exhibits.
The Monterey Bay Aquarium Online - See the aquarium live or tour the exhibits.
Observatorium - the latest space pictures from NASA.
Oregon Museum of Science and Industry - for upper elementary mostly, includes MPEG and Quicktime movies.
Parents and Children Together Online - A Magazine for Parents and Children on the Worldwide Web.
Robert C. Williams American Museum of Papermaking - A Virtual Tour of the Museum.
The Smithsonian Institution
WonderKorner "answers to Curious Questions posed by kids like you".