To enjoy the privileges of copyright protection, registration is not obligatory, however you see more and more people as well as companies legally register their works at the U.S. Copyright Office. What are the benefits of this move?

Public record of your ownership – Your work will be available to the public due to the publication in the Copyright’s Office Catalog. Ownership claim is stronger this way and it is something that is many times contested in copyright infringement disputes.
Maximum damages – Registering your copyright within 3 months from the publication of your work gives you the ability to request statutory damages as well as attorney fees. Even if infringement is proven, it’s many times hard to calculate how much did it harm the copyright owner without the copyright registration.
Validity of copyright – Usually in copyright infringement cases, while you are trying to prove your copyright ownership, the other side will try to prove the opposite. Having your work registered previously gives you strong evidence than simply publishing your work.
Ability to sue in federal court – You cannot enforce your rights as a copyright holder when it comes to bringing a lawsuit for infringement unless your work is registered in the U.S. Copyright Office

What other benefits would you add to this list?