I posted this in the shoutbox the other day, but I can't get over how helpful and informative these are. Yahoo posted some tutorial/introduction videos called the Yahoo! UI Library. It's basically a collection of videos that were (mostly) shot at Yahoo internal workshops on the JavaScript language and using JavaScript tools with the Yahoo User Interface Library (YUI).

The videos I've finished watching so far is the introduction on the ins-and-outs of the JavaScript language by Yahoo JS Architect Doug Crockford. With sites like Yahoo and Google using JavaScript to create great webapps and sites like Digg with it's great user interface, which is powered by AJAX, I knew it was high time I finally put a saddle on JavaScript. For much too long I thought JavaScript was a PHP wannabe and I poo-poo'd it for quite a while. After seeing the "big dogs" like Yahoo and Google put it to good use, I realized I was mistaken. I've tried to read and understand JavaScript syntax and structure before from different books, but I've found these videos to be super helpful in explaining the usage of JavaScript and the structure of the DOM.

So, if you're at all interested in learning more about JavaScript or what Yahoo's doing with it in the form of the YUI, check out these videos.

update: I found this interesting and pertinent enough to be added here. O'Reilly.net has a good article on migrating PHP applications to AJAX. It covers a bit of AJAX terminology and it's associated technologies (JSON, XMLHttpRequest, et al).