Anima App - Design, get feedback, convert to code, publish, iterate.
Sketch Repo - Collection of resources for anyone who uses Sketch
Build with Sketch - Free LEGO-like kit for Sketch
Git Sketch Plugin - Version control for designers
Icon Slate - Icon Slate lets you easily compose, import and export desktop icons in many formats.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.