Today The Design Weblog had a great link to a video illustrating a proposed improvement to the Windows drag and drop interface that they are calling Fold n Drop. I love drag and drop, and am constantly amazed at how few people actually use it. Sure it has some issues, software developers could stand to do more to support it in their apps, but everyone should look into it and get to know the basics at least.
In the mean time, check out Fold n Drop.