The Software Alchemist

I'm reading Secrets of the Javascript Ninja by John Resig. I'd strongly recommend to most developers who do anything with the web that they should read this book.

To be more precise...
Developers who need to read this book:

• Anyone who has written basic JavaScript, but feels a little uncertainty about the phrases 'closure' or 'prototype'
• Anyone who writes JavaScript, but relies on a third party library such as jQuery or MooTools

Developers who don't need to read this book:

• Anyone who hasn't developed a web / JS app (read something more introductory, then this book)
• Valerio Proietti

I've only covered about a third of what has so far been written (covering unit testing, functions, closures and prototypes). But... these fundamentals are of inestimable importance to a developer who has made do with applying knowledge from OO languages to JavaScript.