ASP.NET MVC
Always I am very much fan of MVC (Model, View, and Controller) design patterns. Now on top of .NET Framework 3.5 it is available as ASP.NET MVC Framework.
http://en.wikipedia.org/wiki/ASP.NET_MVC_Framework
ASP.NET MVC Beta Released
http://weblogs.asp.net/scottgu/archive/2008/10/16/asp-net-mvc-beta-released.aspx
http://www.hanselman.com/blog/ASPNETMVCBetaReleasedCoolnessEnsues.aspx
ASP.NET MVC CodePlex Preview 5 Installer + Source
http://www.codeplex.com/Release/ProjectReleases.aspx?ProjectName=aspnet&ReleaseId=16775
The ASP.NET MVC download from Microsoft downloads
Videos