Select Similar Layers - Sketch plugin to select layers with the same attributes
Base UI Sketch Framework - Huge set of everything you need to design and prototype
Framer Inventory 3 for Sketch - Import states & export prototypes from Sketch to Framer
SketchCasts - A weekly screencast, all about how to use Sketch
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.
UiSketcher - Easily sketch user interface with your pen-enabled device!