UPDATE (Nov 2015): In this day and age if you want to have a drop menu there are plenty of arguably better ways to implement one. This answer is a direct answer to a direct question, but I don't advocate this method for public facing web sites.
UPDATE (May 2020): Someone asked in the comments why I wouldn't advocate this solution. I guess it's a question of semantics. I'd rather my users navigate using and kept
for making form selections because HTML elements have semantic meeting and they have a purpose,
anchors
take you places, are for picking things from lists.
Consider, if you are viewing a page with a non-traditional browser (a non graphical browser or screen reader or the page is accessed programmatically, or JavaScript is disabled) what then is the "meaning" or the "intent" of this you have used for navigation? It is saying "please pick a page name" and not a lot else, certainly nothing about navigating. The easy response to this is
well i know that my users will be using IE or whatever so shrug
but this kinda misses the point of semantic importance.
Whereas a funky drop-down UI element made of suitable layout elements (and some js) containing some regular anchors still retains it intent even if the layout element is lost, "these are a bunch of links, select one and we will navigate there".
Here is an article on the misuse and abuse of