Really Good UX - A library of screenshots for UX inspiration
UX Flow Wireframe Prototyping System - Create beautiful user flows prototypes for your next project
Usability.gov - Resource for user experience (UX) best practices & guides
Prototyping Tools - Find the Prototyping Tool You Need
UX Check - Easy heuristic evaluations on your website (chrome ext.)
Userflows - Automatically generate user journeys