In this video we see how Microsoft ASP.NET AJAX helps web developers make network callbacks directly from client-side script code. We see also how an ASP.NET AJAX-enabled web service generates the JavaScript needed to call the web service.

In this video you will learn how to add dynamic partial-page updates to your ASP.NET application using Microsoft ASP.NET AJAX. In particular, you will see how to use the TimerControl to manage the frequency of the AJAX callbacks.

I figured I'd add another one that covers the process of updating a database with the results of drag/drop with an Ajax call. Each time the user changes an item's position in the list it updates the database.