I have to get this information out:
Tux Paint is amazing.

I tried
Tux Paint a year or so ago and thought it was annoying and featureless. A couple months ago I tried it again, my mind has changed. Avery, now about 3 years old, loves it.
Tux Paint is a paint program aimed at kids 3-12. You can paint freehand, draw shapes, use stamps (animals, cars, flowers, etc.) and use effects. It also has some pre-set backgrounds, including an airplane and a castle. It makes sounds as you paint and when you click on animal stamps. It also has the ability to save drawings and print plus many other customizable options (like locking down all keystrokes on computer so your kids can ONLY use Tux Paint until the program is exited).
This program reminds me of the experience I had with Apple IIgs when I was very young. All I knew of the Apple IIgs was that you could paint things on it and then make the picture come out of the printer. I was always puzzled that the dot-matrix printer we had didn't print my drawings in color.
So if you have or know anyone from 3-12, install
Tux Paint for them.
Its available for Linux, Mac and Windows
here. If you are running Ubuntu, just go to "Add/Remove Programs" and search for "Tux Paint". If you are running Windows, just switch to Ubuntu.