Anima App - Design, get feedback, convert to code, publish, iterate.
SketchCasts - A weekly screencast, all about how to use Sketch
Sketch Repo - Collection of resources for anyone who uses Sketch
Base UI Sketch Framework - Huge set of everything you need to design and prototype
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Remake - A way to make web apps with just HTML & CSS