General Overview

There is no "top" to the World-Wide Web. You can look at it from many points of view. Here are some places to start:

The Virtual Library: A classification by information by subject. Includes links to other known virtual libraries.
HTTP servers: All registered WWW native "http" servers, by location.
Servers by type: if you know what sort of server you are looking for.
About WWW: About the World-Wide Web global information sharing project

Starting somewhere else

To use a different default page, perhaps one representing your field of interest, see "customizing your home page".