I have seen a recent trend in duplicating the main site navigation in the page footer, not just as small footer links but boldly displayed across the page.
I have heard discussions explaining this as due to the increase in popularity of hybrid laptops (such as surface) or dockable tablets with keyboards, where the user reaches up from their keyboard to touch the screen. The lower menu is therefore easier to reach and the user can effectively keep their hands on the keyboard.
However in practice I have yet to encounter this in any usability studies. In your experience is this a common action?