ASP.NET AJAX Under the Hood Secrets by PageFlakes.com Creator
PageFlakes.com is a cool, award winning, Web 2.0 startup (they were #1 in the Start Pages SEO awards category this year - beating both Google and Microsoft Live). Even cooler, it is built using ASP.NET 2.0 and ASP.NET AJAX.
Omar Al Zabir, the core architect of PageFlakes, recently published a great article called "ASP.NET AJAX Under the Hood Secrets" that discusses some advanced topics involving ASP.NET AJAX's javascript networking library (specifically he discusses batch requests, browser queues, caching, and get vs. post requests). This is a great read if you are looking to build a high-volume site that uses the client-side AJAX javascript libraries and heavily leverages custom network callbacks.
Hope this helps,
Scott