This morning my daughter wanted to stay home and draw while her mother took her brother to the doctor. Since I need to be in the office working today, I said to her, "Let's find a good drawing program for kind for the computer!"

She was gung-ho with that, and a few minutes later we found TuxPaint. As you can see in the screenshot on the right, it has nice big colorful icons, a simple color palette, and is very easy to use. You can also download a number of "stamps" with different shapes, animals, icons, etc.

She's been coloring away now for more than an hour.

Download and Info: http://www.tuxpaint.org/ 

If your kids are younger or you need something a bit simpler, you should take a look at Scott Hanselman's BabySmash! It is great, but you may want to buy a second keyboard for the kid to bang on.