Sentry is a realtime error logging and aggregation platform
A layout and template manager for Backbone.js applications.
Timeago is a jQuery plugin that makes it easy to support automatically updating fuzzy timestamps (e.g. "4 minutes ago").
Supermodel - Minimal Model Tracking for Backbonejs
A library for adding declarative ajax functionality to your website
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.
jQuery's missing utils and special events