||Using the New Callback Manager in ASP.NET 2.0|
|Subject:||Several other good resources|
Here are several other good resources - each of which should work on the .Net 1.x Framework as well.
Implement Script Callback Framework in ASP.NET 1.x: Good, but possibly IE specific
Thycotic Software Ltd - .NET - Remote Scripting Client (without applet) for .NET and ASP: Cross browser compatible - based on JSRS.