Art of Doodling

I was web surfing and came across some art doodling sites. This one is particularly good. http://www.sacreddoodles.com/pages/artworks.htm
I think it would be a very good thing for children to do or even adults when sitting somewhere like the doctor's office.
On another site it said for children, have them each draw a doodle, then exchange them and finish them. That way you get a fresh one. I think it would be a good way to be creative in a looser way. Less structure, more imagination.
I do a form of doodling while listening to the sermon at church. I will draw unusual crosses, stars, flowers. It's something I can do and doesn't need my complete attention.