Wow, Javascript is cool, but it's really hard to find good info on it. Here's some links that were useful for me:

JSUnit - Unit Testing Framework for Javascript
Advanced Javascript
DOM:element - Document Object Model - Element info
DOM Level 1 Core
behaviour.js - Great extension for prototype.js to do behaviour coding which helps to simplify your .html code
rico.js - Add on code for Prototype to do neat AJAX stuff
prototype.js - Essential cross-browser javascript library
Javscript primer
Javascript events
Essential information for prototype.js
Javascript DOM events
addEventListener - For Firefox, but same model is used in prototype.js
Event info
Javascript events - A good summary of the different kinds of events and which objects they correspond to
Easy AJAX with prototype.js
Venkman - Javascript debugger for Firefox
Venkman FAQ
Prototype Meets Ruby: A Look at Enumerable, Array and Hash
Working with Events in Prototype
Event selectors for Prototype
Painless Javascript with Prototype
A short summary of Prototype


Whew!