As I wrote on one of my last blogs I'm working on a new AJAX library for .NET. There are a lot of AJAX JavaScript libraries available, and I will have a look on those who are interesting for the Microsoft .NET Framework. Maybe you have one that is very cool or has a lot of features build-in, let me know! Like other libraries or controls I do not want to replace the default postback machanism of ASP.NET. Also some libraries are using a own Page, or using an interfaces that you have to deal with. I still will use something like a automatic register helper method.
One thing: can you tell me if you would build Web Services instead of the Ajax.NET methods, of if you love the attribute use? What kind of return values are you using? I'm also interested in any online available web sites that is using Ajax.NET to see what kind of applications you are developing with it. If you have beta web sites use my contact form to send the URL.