SketchCasts - A weekly screencast, all about how to use Sketch
Git Sketch Plugin - Version control for designers
Base UI Sketch Framework - Huge set of everything you need to design and prototype
Fluid for Sketch - Sketch plugin to make your responsive designs more efficient
Remake - A way to make web apps with just HTML & CSS
Sketch Plugin Course by Design+Code - Enhance your design workflow by creating a Sketch plugin