Select Similar Layers - Sketch plugin to select layers with the same attributes
iOS Design Kit - The newest library of native iOS templates
Framer Inventory 3 for Sketch - Import states & export prototypes from Sketch to Framer
Sketch Repo - Collection of resources for anyone who uses Sketch
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.
SketchApp.rocks - Index of all awesome things related to Sketch.