AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.
Really Good UX - A library of screenshots for UX inspiration
Product Hunt - A website that lets users share and discover new products
Usability.gov - Resource for user experience (UX) best practices & guides
Alternative.me - Welcome to alternative.me, the source of better software alternatives. Finding suitable software was never easier.
UX Check - Easy heuristic evaluations on your website (chrome ext.)