jQuery's missing utils and special events
browser-side require() the node.js way
Making AJAX as easy as anchor tags
The fastest, smallest, fully compatible, full-featured asynchronous module!
History.js gracefully supports the HTML5 History/State APIs (pushState, replaceState, onPopState) in all browsers. Including continued support for data, titles, replaceState. Supports jQuery, MooTools and Prototype. For HTML5 browsers this means that you can modify the URL directly, without needing to use hashes anymore. For HTML4 browsers it will revert back to using the old onhashchange functionality.
Awesome handling of keyboard events
A simple, lightweight library making it easy to create routes or run events based on a specific URL hashtag.
Flux architecture tools for React
Create object hierarchies with Backbone models; Respond to hierarchy changes using regular Backbone events.
Webshims Lib is a modular capability-based polyfill-loading library
AmplifyJS is a set of components for data management and application communication.
Timer Object/Class. Kickass!