Design Principles - An open source repository of design principles and methods
Pretzel - Keyboard shortcuts for the app you're currently using
Facebook Design Resources - A collection of free resources made by designers at Facebook
Stacky - Simple app enhancing windows task bar functionality with stacks of shortcuts.
Facebook - Connect with friends, family and other people you know. Share photos and videos, send messages and get updates.
Shortcuts.design - Every shortcut for designers in one place!