Pixel Art Studio - A purpose-built drawing tool for pixel artists
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
Pixel Art to CSS - Draw and animate pixel art, export the results to CSS
Juice FX - Easily turn your pixel art into VFX for your video game.
JS Paint - JSPaint is a web-based Microsoft Paint remake
Piskel - Piskel is a website where designers online create sprites or pixel art.