I prototyped the navigation bar for the Guardian responsive beta site, which is now in production. See the raw prototype and the final product. There’s a writeup of the development process on the Guardian Developer blog.

This idea is this. The “all” link expands a full list of main sections, each with their subsections. The default state of the nav is just the contextual row from the full list, moved up to the top of the (closed) list. The contextual subsection is shifted to the left; it also rotates its siblings leftwards so you can click through all the other subsections on a small screen - without needing to expand the nav. On mobile viewports, the other main sections append to the current subsections and are reachable through a horizontal swipe.