Betafy - Where startups meet beta users!
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.
lucr - Get early adopters for your startup
PitchWall - Browse new startups, and submit your mobile app/games startup's beta page here.
Betatesters.io - The platform connecting mobile developers and beta testers