Several site operators, especially those I’ve talked to who also work in Higher Ed, have found that users (typically students) use their search function a majority of the time over drilling down into the web site to find the information they want. This is true of both first-time and veteran users.
This begs the question that if users are ignoring your navigation and opting for the search engine, should web sites just have a search box on their front page (think Google). A single text input and a search button and that’s it.
Sub-page navigation would be similar; a text input bar along the top that, as you typed in your search string, would display suggestions. This is not unlike Google or the search box in Firefox 3.
It’s an interesting idea. You save a ton of page real-estate. You cater to the individual’s needs rather than trying to guess what they need or how they will perceive the structure of your web site. As long as the user perceives entering text and clicking on the links that appear as more efficient than trying to drill through your navigation scheme this sort of thing would work rather well.
There are, of course, a few drawbacks.
The first is that the traditional search engine would not be able to crawl your web site to index it. You could perhaps add some code that detects search engine bots and produces a site-map (maybe dynamically created).
Users with disabilities may have problems. I’m not certain a blind user would find it convenient. And users that have problems typing would find the interface very difficult.
You could perhaps address both issues by including in your web page a static navigation element that is hidden in such a way that screen readers and search engines will catch it, but regular users will not. Or you could allow users to make the menu appear by mousing-over or clicking a button.
Users who have Javascript disabled may not get the suggestion list, but they could still type in what they want and hit search like a traditional search engine. It just adds an extra step for them, but does not break the functionality of the web site.
The usefulness of such an interface on mobile devices is debatable. While the interface itself would be very small and fit nicely on a mobile device, the user will be forced to type the word or phrase they are searching on. This may be a bigger burden than simply scrolling and clicking on a navigation link or two, but on very deep sites this would probably be an easier interface.
I think the idea is deserving of at least a test implementation.
But perhaps I’m missing some key idea or concept that makes the whole idea break down. Please share any ideas or thoughts you might have.
The Forgettable Mister Ruthsarian 
Some people visit sites not knowing what they are looking for. They want to be able to go to the site and look around to see what it has to offer and what it’s all about. This becomes a little more difficult when your home page consists of nothing but a search box.
I personally rarely use the search feature on sites that I go to often (except in cases where it’s obvoiusly meant to be used often: search engines, video sites where you are looking for certain videos, etc.). I’ve been to the sites enough and spent a little bit of time learning where things are, so I have no need to search.
While I always put a search box in the sites I make – I do hope people aren’t using them. My problem is I always struggle with whether to go with a google website search that improves results but oftentimes leads your viewers yonder – or a customized search engine for your own site – that doesn’t get the high quality of results that a google search gets.