Tux Paint - Tux Paint is a free, award-winning drawing program for children ages 3 to 12 (for example, preschool and K-6).
Kid Pix - Kid Pix is a bitmap drawing program aimed at children.
Drawing For Children - Drawing for Childen is a free drawing program for children with many nice options.
The MagicBook - Free electronic coloring book.
Painty - Kid, if you have a dream to paint the best picture in the whole world, this is the place to start...
Lil' Picasso - Lil Picasso is a coloring and creativity package for children.