PitchWall - Browse new startups, and submit your mobile app/games startup's beta page here.
Product Hunt - A website that lets users share and discover new products
BetaList - BetaList provides an overview of upcoming internet startups. Discover and get early access to the future.
Betafy - Where startups meet beta users!
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.
Launching Next - Showcasing the world's most promising new startups every day