Art for Children - visit The Worldwide Art Directory to find great links to art related sites for kids.
Luis Filella - wonderful whimsical illustrations for children
Surf the Net with Kids - great site for kids and their families with online activities and information as well as great links to other kids' sites.
Crayola Website - online fun with this childhood favourite.
ThePuzzleFactory.com - online games and puzzles to keep kids amused for hours.