Wesley put a 4GB file in a 232KB file system by making some clever modifications to the FAT.
A tiling window manager, written from scratch. Miles used it as his main window manager for a year after writing it.
It's Tinder for birds. A faithful recreation of the real thing (including animations), but with one obvious difference. Written in Elm. Running version at https://pecker.app.
An in-browser IDE for the Piet programming language.
A minimal Go AI modeled on AlphaGo. It became the basis of Minigo (https://github.com/tensorflow/minigo), which is maintained by the Tensorflow team.
A GameBoy Color palette browser that uses your webcam.
Most stores aren't open 24/7. Amazon.com is. This extension makes Amazon.com more like other stores. The new Amazon.com hours are 10am-9pm M-F and 11am-8pm Sundays.
Programmatically generated city guides for imaginary cities. Pictures, maps, places of interest, local language, flora and fauna are all included.
A programming language where every computation happens in a separate Docker container.