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.
Mike Alsup builds up to an elegant plugin development pattern for jQuery plugins, starting with requirements and adding a piece at a time. By explaining the reasoning and though behind each piece of the puzzle, it explains a number of important good parts of the JavaScript language