Addy Osmani introduces backbone.js as one part of the toolkit for building mobile JavaScript web applications. Backbone is an MVC-like framework to structure your application, simplifies server-side persistence, decouples the DOM from data, succinctly separates apps into Models, views and routers and provides synchronisation between DOM, model and collections.
Thomas Fuchs offers a JavaScript powered application that allows developers to filter down to find the most appropriate JavaScript micro-library or micro-framework for their project. There has been an explosion of mini-libraries in the JavaScript world as web developers get to grips with more complex and rich user interfaces and web applications.
Christian Heilmann describes an approach to building complex web application by basing them around events, particularly around YUI's CustomEvent class.