Drawasaurus - Drawasaurus is an online drawing & guessing game you can play with friends or strangers.
Open Peeps - A hand-drawn illustration library.
LetsDraw.It - Guess and Draw, Drawing Battle, Pictionary, Copy picture - online drawing games where you can compare your skill with others.
Control Illustrations - 108 free flat illustrations with customizable characters
skribbl - Word guessing based on drawing.
DrawKit - MIT licensed SVG illustrations, in 2 styles