^you can be sure the admins have close to perfect credit lists! You can check out ForgottenFace, Mercury or Contour's gallery if you need examples.
You can also still include the site you mentioned (morgue) in your credit lists. Like it says in the first post, credit lists are not only to give credit, but also to direct others to your resources.
Once you start making more and more graphics, your credit list will grow steadily longer, even if you don't have many credits at the moment.