Tilf (Tiny Elf) is a free, simple yet powerful pixel art editor
A free & open-source 2D sprite editor, made with the Godot Engine
A canvas you can draw on with different colors
Pixel art and spritesheet editor
You can free remove background from image
Image Converter HTML5 add-on for Firefox
A simple .NET paint in C#.
Development has moved to github
Software for screen capture.
A multiuser web-site for drawing and conversation.