wp_list_sub_pages

This WordPress plugin is oly one function. It takes exactly the same parameters as wp_list_pages, except for child_of, which is used internally.
When called on in template file, it will list :
* on the homepage of the blog, every page and subpage (default, this can be overriden by parameters)
* on every other page, only the pages with the same top-parent (parent of level 1)