SketchBook Express
Some users refer to SketchBook Express as the Mac Version of Windows Paint, but it's more powerful. Created by AutoDesk, it offers casual users an easy way to learn how to paint and draw. Those who know little about drawing and painting will learn the ropes quickly.
A blank canvas greets you after launching the app. One window has controls for redo, undo, colors and shapes. Pencils, erasers, pens and brushes are stored in another window. You also have flood fill tools, brushes for sharpening and blurring.