The Material Theme Editor helps you make your own branded symbol library and apply global style changes to color, shape, and typography. Currently available for Sketch, you can access the Material Theme Editor by downloading the Material Plugin.
Sketch library for user flows/content maps/annotations
Flowkit is a Sketch library that allows you to quickly build out high-level flows to tell the story of your designs—perfect for presentations and documentation. You have full control over intelligently-named symbols and endpoints, making complex flows a walk in the park.