Here's links to some games for younger kids:

Nick Jr. Arcade - Play arcade games or color pictures or create spin art.

Links to Kids Games - Education, Jigsaw puzzles, action games.

PBS Kids - Sprout - Fun games and educational games.

Sesame Street - Play games with all your favorite Sesame characters

N.O.G.G.I.N - Nick, Jr. games

AOL for Kids, Jr. - Lots of fun with colors, letters and shapes

Mother Goose games - lots of music games.

Boowa & Kwala - Hundreds of games for kids up to age 6

Monkey Bar TV, Jr. - Lots of fun games with Mr. Potato Head, Candy Land, My Little Pony, Weebles

Fischer-Price - online games for infants to preschool