Even though I haven't had a chance to use it yet, I felt I should pass along what looks to be an incredible tool for debugging JavaScript - FireBug. I stumbled upon it via this great writeup:
An in depth look at the future of Javascript Debugging with FireBug
The more and more true Javascript that I write, the more I find the need for a solid debugging platform. Moving away from the venerable "alert debugging" so many of us are used to. It's one thing when all you're doing is hiding and showing DOM elements. However, take for instance my Flickr Notes implementation. For that, and any increasingly complicated applications, you simply NEED to be able to debug.
So, check out FireBug... I am certainly going to.