Per a request in one of the WordPress support forums I still frequent, I’ve written a quick little filter plugin that allows you to hide the download link to a file and only display it when the viewer is logged in. A lot of forums have this feature, usually as a plugin, to forse users to create accounts on their forums.
Usage is fairly simple: [user_download URL] where URL is the URL of the file in question. Visitors who are logged in will see the URL while others who aren’t logged in will see the standard “You need to be logged in…” message.
Feel free to use. Please consider a link back if you find some use for this.