Hierarchical Menus with the Underrated style.display Object
http://www.oreillynet.com/pub/a/javascript/2002/02/22/hierarchical_menus.html

Pena, Bill
O'Reilly and Associates
2002

Abstract:

One of the most common DHTML requests I get is for a Windows Explorer-style hierarchical menu, where there's a list of topics or 'folders' that a user can click on to reveal subtopics, or 'files,' within that folder. It's a common desktop metaphor that seems ever more necessary on the Web, especially as we see navigation bars incorporating larger and more complex content while still trying to fit on the screen. Hierarchical menus are a solution to the common problem of having too many links in too small a space.