Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
Pixel Pix - Turn your photos into pixel art
Pixel Studio - The Pixel Art Is Always Fun
Voxel Builder - Design and edit 3D voxel models in your browser.
Pixel Art to CSS - Draw and animate pixel art, export the results to CSS
Da Vinci Eye - Learn to draw by using your phone to overlay images for you to trace