Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.
WebEdit Professional is a simple and powerful browser-based application that enables any non-technical user to create, edit, and manage their entire website. It features access control, file management capabilities, and the ability to edit and create new files within a WYSIWYG editor, and templates.
Allegro Sprite Editor (ASE) is a program specially designed with facilities to create animated sprites that can be used in some video game. It lets you create static images, characters with movement, textures, patterns, backgrounds, logos, color palettes, etc. It focuses on pixel editing to do pixel art. It isn't a photo retouching tool or a vector graphics editor. Mainly, it is a tool to create tiny animations pixel-by-pixel.
JPatch is an amazing 3D Modeling/Animation tool designed to model and animate "organic" shapes such as humans, animals, aliens, etc. It is a bezier-spline modeler and works with so-called "Coon's patches", the same patches that are used by the popular Windows freeware modellers sPatch and Hamapatch and the commercial program Animation Master (they are called Hash patches there). JPatch is written entirely in Java.