Snap Art - Snap's augmented reality platform
Pixel Art Studio - A purpose-built drawing tool for pixel artists
Low Poly Art - World's largest free collection of low polygon backgrounds
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
Da Vinci Eye - Learn to draw by using your phone to overlay images for you to trace
Pixel Art to CSS - Draw and animate pixel art, export the results to CSS