Training for non-tech site users

Does anyone know of a good set of instructions, text or video, for training Users — e.g. Contributors, Authors, and Editors — people who are going to be creating content but not doing any work on the theme?

I find that training people to use a site properly is an important part of creating a successful site, but one that I often forget to consider before I get there. There is no use in creating an elegant site if the people who are creating the content are afraid of the technology. Often things that seem perfectly obvious to me — like the difference between a Post and a Page, or how to insert an image — baffle the writers, photographers, and others who are actually creating content for the site.