PitchWall - Browse new startups, and submit your mobile app/games startup's beta page here.
SimilarPages.com - SimilarPages has found and classified millions of interesting sites hidden due to low popularity with the goal of helping you discover and search a larger portion of the web
Product Hunt - A website that lets users share and discover new products
SimilarSites - Easily find more sites like those you like.
The Startup Pitch - A place for startups to share themselves with the world.
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.