MoreGamesLike.com - Most popular recommendation engine for more similar games and recommendation blog.
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.
Open Source Game Clones - This site tries to gather open-source reimplementations of great old games in one place.
Alternative.me - Welcome to alternative.me, the source of better software alternatives. Finding suitable software was never easier.
Alternatives By TechnoFizi - Find all major games, apps, sites, software alternatives
Product Hunt - A website that lets users share and discover new products