Ayman Hourieh covers some interesting manipulation of Arrays that accommodates typical data structures. He also covers how to bind methods to objects, sorting with custom functions. He shows a custom AssertException, and covers using Firebug for debugging. He covers some JavaScript quirks: static local variables, null, undefined and delete.
Based on Simon Willison's original 2005 eTech talk, Simon expands this into a full article covering the expressive functionality of JavaScript. He covers the basics of JavaScript: literals, variables, functions, scope, control flow, objects, classes, inner functions and closures. Everything a developer needs to know before diving into more advanced JavaScript.