humane.js is a simple, modern, framework-independent, well-tested, unobtrusive, notification system.
Utilizes CSS transitions when available, falls back to JS animation when not. Includes mobile support.
Fecha is a lightweight date formatting and parsing library. Meant to replace parsing and formatting functionality of moment.js.
It is also completely library independent and can be safely used next to NodeJS, jQuery, YUI, Scriptaculous, MooTools, etc.
whs.js is a framework for 3D web apps and games built with Three.js technology. It implements a core with component system and plugin support for fast development of 3D scene with physics.
Collect.js is a convenient and dependency free wrapper for working with arrays and objects.
Flubber is a library to provide a best-guess interpolation for any two arbitrary shapes (or collections of shapes) that results in a reasonably smooth animation.
A couple of ideas for typography animations and letter (hover) effects for playful interactions. Anime.js is used to create animations.
t-scroll is a modern reveal-on-scroll library with useful options and animations.