Sketch Repo - Collection of resources for anyone who uses Sketch
Uxcel - The easiest way to learn UX/UI design
Sketch 101 by Designlab - Learn Sketch in this free course w/ downloadable templates
Daily UI - Become a better designer in 100 days
RookieUp Career Bootcamps - Tools to help designers build great portfolios and get jobs.
GoodBrief - A random generator for design briefs.