Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
miniPaint - Online graphics editing tool use HTML5 technologies like Canvas, Offline support, Drag and Drop.
Grafx2 - GrafX2 is a bitmap paint program inspired by the Amiga programs Deluxe Paint and Brilliance.
JugiPaint - JugiPaint is a painting software with diverse tools for various types of illustration work.
Piskel - Piskel is a website where designers online create sprites or pixel art.
Paint +++ - Paint +++ is a native image editor for Mac that enables you to complete everyday image editing tasks in a single place.