There's a sequential ordering to most big websites, a Next and a Prev. Go thru the chain and you'll see everything. There's the concept of a Home, the very topmost page. High flow home pages are very valuble. Check it out.
Search engines make a big difference.
If you don't use Alta Vista, check it out. A new WebCrawler is coming. Distributed search engine software is starting to appear. The art of searching makes the art of structuring possible. They support each other beautifully.