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.
GitSpo - Measure & engage your open-source community
SimilarSites - Easily find more sites like those you like.
Devo - Devo delivers real-time operational & business value from analytics on streaming and historical data to operations.
Product Hunt - A website that lets users share and discover new products
Ruby Toolbox - Explore and compare open source Ruby libraries