LibHunt - LibHunt tracks mentions of software libraries on relevant social networks. Based on that data, you can find the most popular projects and their alternatives.
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.
Ruby Toolbox - Explore and compare open source Ruby libraries
GitNews Web - Trending repositories from GitHub, HackerNews & Reddit
Libre Projects - A directory of free & open source hosted web applications and alternatives to many proprietary...
Good First Issue - Make your first open-source contribution