skribbl - Word guessing based on drawing.
Conceptboard - Instant Whiteboards for Teams & Projects
LetsDraw.It - Guess and Draw, Drawing Battle, Pictionary, Copy picture - online drawing games where you can compare your skill with others.
OpenBoard - The OpenBoard software is an interactive white board software.
gartic.io - Draw, guess, and win!
Microsoft Whiteboard - The canvas where ideas, content, & people come together.