Let's draw is a webapp where you can draw. While you are drawing others can also draw. Basically you can draw with other people, all on the same canvas.
I made this to make myself familiar with websockets. I also learned a lot about node.
Do you want to host this yourself?
Clone the project and go into the folder. Make sure you have npm installed and run npm install in the folder. Now you can change the config.js file to select a host and port. After that you need to go in the public folder and edit sketch.js. In the line socket = io.connect('http://localhost:3000'); you should replace the url with the one you use to acces the site. That is it. Go back to the project root and run nodejs server.js.
This project is inspired by a video series off Daniel Shiffman.