Eve.js
A <3kb JavaScript file providing three simple methods to organize code into CSS namespaces which magically restrict code to the current context, allowing for dramatic reductions to code size and development time.
Kefir
A Reactive Programming library for JavaScript
Modules Webmake
Bundle CommonJS/Node.js modules for web browser
Hermes.js
Message and Error logger implementation
Pegasus
Load data while still loading other scripts and display data faster in jQuery, Backbone, Angular, ... apps
Bootstrap Ajax
A library for adding declarative ajax functionality to your website
Autolink Js
Tiny little tool to find URLs in a string of text and hyperlink them
Tock
Timer Object/Class. Kickass!
Lunr.js
A bit like Solr, but much smaller and not as bright
Loglevel
Minimal lightweight logging for JavaScript, adding reliable log level methods to wrap any available console.log methods
Fluxxor
Flux architecture tools for React
Sentry
Sentry is a realtime error logging and aggregation platform
Theory
Abstraction layer for cross platform JavaScript.
Lucid Js
LucidJS is a chainable event emitter library. It offers several unique features such as set events, emitter piping, DOM node encapsulation, sub events, along with the usual event triggering and binding. LucidJS emitters also feature meta events that allow listening for event binding and event triggering. LucidJS works in both the browser and node.js.
Jquerypp
jQuery's missing utils and special events
Backbone React Component
A bit of nifty glue that automatically plugs your Backbone models and collections into your React components, on the browser and server
Steal
Gets JavaScript