Really Good UX - A library of screenshots for UX inspiration
Laws of UX - Key maxims that designers must consider when building UX
Usability.gov - Resource for user experience (UX) best practices & guides
Owletter - Keep an Eye on Your Competitors' Newsletters
UX Check - Easy heuristic evaluations on your website (chrome ext.)
CleverAnalytics - Competitor analysis & tracking of customer loyalty software