Terry is right about menu bars being JS. Not only do the search engines miss them, but sitemap generators aren't too clever at picking them up either.

I just changed my text menus for menu bars and my site went from 125 pages to 17 according to the new sitemap. The easiest way to fix this is to avoid menu bars altogether and use a simple text menu.

Another point to bear in mind is the user. IE in Vista is ridiculously restricted and will not display a JS menu unless the user jumps through a load of hoops, which may be fine for me and you, but could frighten off a number of inexperienced users.