A Game a Day

http://www.agameaday.com/

Enjoy a new game, brain teaser, trivia game and challenge your concentration, memory and knowledge. One new game each weekday for ages 9-99.

Cartoon Network

http://www.cartoonnetwork.com/games/all_games/index.html

Not that you need a link to a site you've got memorized!

Discovery Kids

http://kids.discovery.com/games/games.html

Games, puzzles, mind teasers and more on this site - be sure to check out the Yucky Fun & Games! for Creepy Crafts, Revolting Recipies and Icky Experiments!

Fun Brain

http://www.funbrain.com/

Play games that make you smarter. Oh, and by the way, you can read Diary of a Wimpy Kid by Jeff Kinney online here!

Fun School

http://funschool.kaboose.com/

What?!?!? Fun and School in the same sentance?  Yes kids, that's right. Tons of games are found on this site for all ages from Preschoolers to Middle Schoolers.

GWAP

http://www.gwap.com

A collection of free online games involving competitive tagging. Sign up, but no fees. Does you get lost in games like solitaire? Those hours can help make The Web a better place!

PBS Kids

http://pbskids.org/go

There are tons and tons and tons and tons of games on this site!

Professor Garfield

http://www.professorgarfield.org

Games about art, music, science and math. There are even phonics games for younger children!