Hyper - Extensible, cross-platform terminal built on open web standards.
Frontend Mentor - Supercharge your front-end skills by building in a real-life workflow. Solve real-world HTML, CSS and JavaScript challenges whilst working to professional quality designs.
VUIchallenge - Daily challenges to improve your voice design skills
A Product Design Challenge - Get a design challenge to solve real-world problems
Herd - A marketplace for online support groups.
Singscope - See your pitch analyzed as you sing