Our site is pretty old and the navigation is currently a large list of links on the left side of our page. (We use CSS similar to suckerfish to collapse it)
Our site is mainly informational, with topics from news releases to science papers to social media links and multimedia.
How to make effective top navigation? Use a classic top nav with contextual side navigation? How many menu items become too many? How much of the page should be dedicated to navigation? What sort of principles guide the decision as to where something goes in my menus?
This is a .gov site, therefore much of the content is esoteric and not for everybody. However if you need it, you really need it. And in our case, about 50% of our visitors are probably looking to argue with us (meaning they are on the hostile side to begin with)