Google Directory
In looking for information on the web, there have long been two basic approaches -- Computer-driven search engines work best for "needle in a haystack" searches and people-produced search directories work best for browsing in broad subjects. In the last couple of years, this separation between search engines and search directories has begun to break down, as several of the standard search engines have added nominal search directory components.

Google is the hot new search engine that ranks sites by their "importance" on the web, based on the volume and "authority" of other sites linking to them. Google is a "pure" search engine with no associated search directory component. But -- Interesting discovery -- If our experience in health/medicine is any indication, Google can be used quite successfully as a gateway to high-quality, subject-specific search directory sites.

Using Google to find directory sites
Experienced web researchers soon learn, in looking for information on specialized subjects, that the key is often finding a well-maintained "list of links" on the subject, otherwise known as a directory site. Finding these, however, can be difficult. Since its conception in 1995, the purpose of the Hardin Meta Directory of Internet Health Sources (Hardin MD) has been to provide access to the best directories in 38 clinical medicine specialty fields.We've recently discovered that searching in Google for the names of these medical specialties turns up a remarkable phenomenon -- Almost invariably, in the first 100 hits in the Google search (out of several thousand hits total), many of the directory pages appear that we list in the Hardin Meta Directory! Why? Because the Google search engine is smart! -- Intelligent humans learn from experience with the Net that directory sites are important, and so they do the obviously human-smart thing and put links to directory sites on their pages. Google, finding these many links, is able to take advantage of this accumulated human-smartness, and that's why so many directory sites come to the top in Google searches.