Slack - A messaging app for teams who see through the Earth!
PaintBerri - PaintBerri is a free art site that offers an awesome oekaki community.
Sketchboard.io - Visual Remote Teamwork. Solve problems and create ideas on endless whiteboard with your teammates by sketching.
okekai - A small community site where you can draw, animate, and chat through pictures all for free
Smoothboard Air - Smoothboard Air is a collaborative interactive whiteboard application for iPads and Android devices that revolutionizes interaction in lecture rooms.
Brush Ninja - Hand-drawn Animated Gif Creator