Better Late Than Never - Register Your Published Photographs
Pursuant to a recent change in copyright law, you now can register a group of published images on one form. The only requirements are that the photos must have been published in the same year, made by the same photographer and have the same copyright claimant. This should fit the profile of most photographers and their work.
Specific instructions on how to prepare your registration forms for published photographs are available from the Picture Archive Council of America at http://www.pacaoffice.org/copyright.html in "The Importance of Copyright Registration"
You no longer have an excuse. Go to the dentist, change the oil in your car, and register your images, both unpublished and published. It's better late than never.
Take my advice; get professional help.