DART (www.dart.com) has a suite of ASP.NET controls that parallels Microsoft's ASP.NET server controls found in System.Web.UI.WebControls.
LiveControls are both cross-browser compatible and can communicate with the server without refreshing the page.
In addition, nothing is used except common DHTML/remote scripting techniques. There is no use of Flash, Java, or other plug-in technology.
The Latest version 1.1.3 supports .NET version 2.0!
DART claims the controls to be the first commercially available AJAX toolkit for ASP .NET
I am thinking of this suite to be my option for ASP.NET devolopment and hoped to hear any feedback from the community if anyone has used them