I think for some designers the standard conventions for things like navigation (across the top or on the left, typically) seem too confining. But to put the navigation below the fold, as you mentioned, is kind of like deciding to place a book’s table of contents at the end of the book instead of at the beginning.

Every now and then, a client hires an external web designer (usually the same people who do their print design) to create mockups of a site, and then hire my employer to build the site. We find that print designers often struggle with usability issues. Some times they put the entire navigation system “below the fold,” for example. On a page with enough content, that means users have to scroll all the way to the bottom to navigate to another page.

Then there are others that don’t think out how a user will navigate the site. Some site sections have a home page, whereas others are just a category of pages with no home page to bring them together.

But I guess that sort of thing is prone to happen when you design something but never really get involved with building it. That simple premise is a handy explanation for why I can’t design a car or a house!