If you look in the theme config.php you'll see this switch:
$THEME->makenavmenulist = false;
/// By setting this to true, then you will have access to a
/// new variable in your header.html and footer.html called
/// $navmenulist ... this contains a simple XHTML menu of
/// all activities in the current course, mostly useful for
/// creating popup navigation menus and so on.
/// By setting this to true, then you will have access to a
/// new variable in your header.html and footer.html called
/// $navmenulist ... this contains a simple XHTML menu of
/// all activities in the current course, mostly useful for
/// creating popup navigation menus and so on.
You can then include the XHTML in your header or footer, and combine it with Javascript to create menus that work/look like the floater on this page, for example (look in the top left):
http://www.thailandguru.com/infra-electricity.html