Excellent Ajax library that allows working with .NET stuff directly.
Did you have a look at the beta version of Ajax.NET Professional? More security features like AJAX Token, encryption on client-side JavaScript and on the server, faster JavaScript wrapper files cached using HTTP ETag header values, using Namespaces on the client-side JavaScript to ensure that there are no variable name conflicts, a fully new written JSON parser that will allow you to use any object as method argument or result value without writing an IAjaxObjectConverter.
The library looks extremely useful and can be used in a variety of projects.