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!
PitchWall - Browse new startups, and submit your mobile app/games startup's beta page here.
Beta Family - 50,000 testers to test your app
StartupBase - Community of makers & early adopters