Betatesters.io - The platform connecting mobile developers and beta testers
Toshi - A browser for the Ethereum network
Betafy - Where startups meet beta users!
MyEtherWallet - MyEtherWallet is a free, open-source, client-side interface.
Beta Family - 50,000 testers to test your app
Exodus.io - All-in-one app to secure, manage and exchange blockchain assets.