Wow
Reveal CSS animation as you scroll down a page
React Virtualized
React components for efficiently rendering large lists and tabular data
Fragment.js
A tiny tool for easily loading html fragments and templates
Voyeur.js
Voyeur is a tiny (1.2kb) Javascript library that lets you traverse and manipulate the DOM the way it should have been.
Vissense
A utility library for observing visibility changes of DOM elements.
Bonzo
library agnostic, extensible DOM utility
jQuery.nicescroll
nicescroll plugin for jquery - scrollbars like iphone/ipad
Eqcss
EQCSS is a plugin that introduces Element Queries, Scoped CSS, a Parent selector, and responsive JavaScript to all browsers IE8 and up
jQuery Evergreen
Small & fast DOM and event library for modern browsers.
Bind.js
bind.js - simple two way data binding to HTML and callbacks
Interact.js
Drag and drop, resizing and multi-touch gestures with inertia and snapping for modern browsers (and also IE8+)
Hapi
The Simple, Secure Framework Developers Trust
jQuery.lazy
A lightweight, fast, feature-rich, powerful and highly configurable delayed content, image and background lazy loading plugin for jQuery & Zepto.
Node List.js
NodeList implementation/library - Use the Native DOM APIs as easily as jQuery
Packery
bin-packing layout library
Veinjs
Injects CSS into the document (it's a perfectly legal procedure)
Turbolinks
Turbolinks makes navigating your web application faster