O’Reilly’s ONDotnet:
One of the benefits of using a windowing system is the ability to drag and drop objects from one window to another. Such is the functionality that we have taken for granted when using Microsoft Windows. Though it seems such a trivial task, not much has been written about how to implement drag and drop in your Windows application. In this article I will discuss how you can use Windows forms using the .NET Framework to develop applications that support drag and drop operations.
[via Phillip Pearson, who got it from Rick the techno-weenie]