Beanie Babies
BlackDog's Games
Castles for Kids
Crayola
Fact Monster
FunBrain
Hands on Crafts
Idea Box
Jigsaw Puzzles 
John's Word Search Puzzles
KidsCom
Kids Domain
Kids Play Safe
Kinetic City Cyber Club 
Lullabies and Other Songs for Children
National Gallery of Art for Kids
Peanuts (Snoopy)
Pikachu Dance!
Pokemon
Primary Games (for elementary children)
Star Wars
White House for Kids
Yo-Yo Universe

Above and Beyond Children's Museum
Chicago Children's Museum
Exploratorium

How Stuff Works
National Zoo

American Youth Soccer Organization
Junior Links Golf Site
Major League Baseball
Kid's Dugout
NFL
Packers Kids' Zone
SkateWeb: The Figure Skating Page

Muppets
Nick Jr.
PBS Kids