An application creating a temporary folder on your desktop.
Why? I personally use the Windows desktop as a place where to drop files I need to reaccess fast in the next minutes our hours for a certain task - and those files can be deleted after the task is done. This application creates an empty folder on startup and deletes the old folder from your last startup so you always start with a clean desktop.
Download the application JAR (or build it yourself) and add a shortcut to the autostart menu.