FLOW

Flow is a drawing tool that allows you to create animated screen drawings using a variety of stamps and brushes. Good fun to combine all of effects.

http://www.nga.gov/kids/zone/flow.htm

http://www.nga.gov/kids/zone/flow.htm

ArtPad

This is very cool in so many ways. I love the fact that you can replay the drawing. This would be an excellent way to illustrate a technique or show someone how to draw a specific object. But equally so it is just a great way to show off your drawing skills.

http://artpad.art.com/artpad/painter/