miniPaint - Online graphics editing tool use HTML5 technologies like Canvas, Offline support, Drag and Drop.
Drawasaurus - Drawasaurus is an online drawing & guessing game you can play with friends or strangers.
RealWorld Paint - RealWorld Paint is an free portable image/photo/animation editor.
gartic.io - Draw, guess, and win!
Paint XP for Windows 7 - Standalone old MS Paint program that allows you to get your old XP Paint interface in Windows 7.
skribbl - Word guessing based on drawing.