Tux Paint is a free drawing program designed for young children (kids ages 3 and up). It has a simple, easy-to-use interface, fun sound effects, and an encouraging cartoon mascot who helps guide children as they use the program. It provides a blank canvas and a variety of drawing tools to help your child be creative.
Pros: Tux Paint is a fun and interactive painting application for children of all ages (including some adults). Tux Paint is a cross-platform application for Mac, Windows, Linux, Free/Net/OpenBSD, and Solaris.
Cons: The stamps are only available as a separate download.