PaintBerri - PaintBerri is a free art site that offers an awesome oekaki community.
Draw.Chat - Anonymous real-time whiteboard with text and video chat.
Brush Ninja - Hand-drawn Animated Gif Creator
Limnu - Sketch, share and collaborate with your team
okekai - A small community site where you can draw, animate, and chat through pictures all for free
Sketchboard.io - Visual Remote Teamwork. Solve problems and create ideas on endless whiteboard with your teammates by sketching.