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.