This page is especially for kids. 

http://gardenofpraise.com/bibleles.htm#new

This site has old and new testament lessons available.  There are songs and online games to go with each lesson.  There are also printable worksheets available.

Age appropriate: 2 - 10

http://wolfeborobible.com/teen.html

A great site for Teenagers!! This site really ask the questions and gives the answers that your children want and need to hear.

Age appropriate: 13 and up