Blank Canvas, 2016, Ethereum Contract and HTML/JavaScript/CSS.
A blank canvas that anyone can set the colour of on the Ethereum blockchain.
The images above show use of the GUI to change the colour (the GUI appears if you click in the window displaying the canvas).
You can download the interface code here, it’s in the dapps/blank-canvas directory.
To use it you’ll need an Ethereum node running locally, and to change the colour you’ll need some Ether.