BetaList - BetaList provides an overview of upcoming internet startups. Discover and get early access to the future.
Betafy - Where startups meet beta users!
Product Hunt - A website that lets users share and discover new products
PitchWall - Browse new startups, and submit your mobile app/games startup's beta page here.
lucr - Get early adopters for your startup
Startup Buffer - Startup Buffer is a premium startup directory for emerging startups all around the world.