DrawPile - Drawpile is a drawing program that lets you share the canvas with other users in real time.
PaintBerri - PaintBerri is a free art site that offers an awesome oekaki community.
Aggie.io - Draw a picture together with your friends in real-time over the internet in your browser.
slimanimation - to make stick figure or hand drawn animations
FlockMod - Flockmod is a free real time online group drawing app with all the bells and whistles.
FurAffinity - Fur Affinity, the internet's largest online furry art community.