An award-winning drawing program for children of all ages
A simple LaTeX {picture} drawing tool
Vector drawing program for LaTeX using PSTricks
Pencil2D is a cross-platform animation/drawing application.
Madeline 2.0 Pedigree Drawing Engine (PDE)
Free drawing software for Windows, Mac OS X, and Linux
OBSOLETE; try http://drawpile.net/ instead!
Vector based drawing software designed for RPGs