Bruce,

>Also, a new term has arisen in connection I have not before heard: "Extranet." What is this, something like a WAN Intranet?

Generally, Extranet refers to a web site that is more public than an Intranet, but perhaps not fully public.

Usually you see the concept used in connection with a company's customer relations and interactions, or between businesses. For instance, think about a stock trading site that requires security to get into your account information, an order-tracking system for a mail-order company, a customer relations site set up just for large, important customers.