Tux Paint - Tux Paint is a free, award-winning drawing program for children ages 3 to 12 (for example, preschool and K-6).
MathIsFun Times Table - Learn Your Multiplication Tables
Kid Pix - Kid Pix is a bitmap drawing program aimed at children.
GCompris - Educational Game for Children 2 to 10 years old.
Painty - Kid, if you have a dream to paint the best picture in the whole world, this is the place to start...
childsplay - Childsplay is a collection of educational activities for young children and runs on Windows, OSX, and Linux. Childsplay can be used at home, kindergartens and pre-schools.