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.

The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.

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.

wikiHow - wikiHow is a wiki based collaboration to build the world’s largest, highest quality how to manual.

JSter - JSter is a community-driven catalog of the most useful javascript libraries.

AllAnswered - Your Team's Collective Brain All-In-One Knowledge Management System Wiki + Q&A + Workflow + AI