Michael Schwarz, a .NET developer in Germany has released the latest version of his Ajax .NET Wrapper. This class library simplifies the use of XMLHttp by providing .NET objects that generate the necessary Javascript code.Documentation is scarce, but he does have examples in both C# and VB.NET showing how to use the classes to make server requests that return data in the form of primitive types, Datasets, and even .NET objects.
More at:http://weblogs.asp.net/mschwarz/archive/2005/04/07/397504.aspx