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.
ScrollMagic - The jQuery plugin for magical scroll interactions.
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.
Lax.js - Create beautiful & smooth animations when you scroll
JSter - JSter is a community-driven catalog of the most useful javascript libraries.
WOW.js - Animate elements on-scroll to catch attention. Such Magic.