Real Desktop Light
Real Desktop Light doesn't merely dress up your desktop--it thoroughly transforms your desktop into a three-dimensional one. More than that, though, the objects on your desktop become virtual objects that you can rotate, move, and even throw against one another. They react just as if they were real-world objects; they have weight and physical dimensions, and behave accordingly. For example, when you throw one object against another, the items crash, clink, and slide.
You'll find a lot of playfulness in Real Desktop Light (the Recycle Bin, for instance, becomes a 3D trash can). But you'll like the app not just for its whimsy but also for its usefulness. It makes finding what you want on your PC much easier.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.