Google:

Over 15 million players have contributed millions of drawings playing Quick, Draw! These doodles are a unique data set that can help developers train new neural networks, help researchers see patterns in how people around the world draw, and help artists create things we haven’t begun to think of. That’s why we’re open-sourcing them, for anyone to play with.

Load the Quick, Draw! data page and click on a drawing to see a ton of sketches of that same subject. The data underlying Google’s Quick, Draw! game is fascinating and it is now open sourced.