Maps help us navigate. On the Internet, finding things has become the big challenge. Death by a thousand clicks is the bane of any net user. The Internet is a network of many metaphors. The core infrastructure supports many protocols, and each protocol adopts a metaphor.
Electronic mail uses analogies taken from a postal service.
Streaming media started with a radio metaphor before evolving into a unique medium. As we look at a page on the Web, the logical next step is to find other pages that are conceptually near. Near, of course, varies on your point of view. Meta-information is what helps the Internet become smarter about organizing itself. As we develop the tools to describe Internet resources, to manage meta-information, maps will happen.