Base UI Sketch Framework - Huge set of everything you need to design and prototype
Fonts In Use - Type in the real world: an amazing archive of typography.
INSTAD.IO - Automagically converts vector images into sketchy style
Typewolf - Typewolf helps designers choose the perfect font combination for their next design project—features web fonts in the wild, font recommendations and learning resources.
Sketch Extensions - An official collection of Sketch extensions & plugins
Google Fonts - Making the web more beautiful, fast, and open through great typography