Web.UI 3.0 for ASP.NET combines ComponentArt’s unique rendering technology with the power of AJAX to deliver the most advanced set of user interface controls available for ASP.NET. Now featuring ALL NEW Grid, Callback and Calendar controls.
I am currently using the Menu control from this ASP.NET controls suite on Tech Head Brothers website. I started some trial of there suite with ASP.NET 2 and especially the Callback control and was able to create a small forum in no time with Ajax/Callback getting each message on user click.