In the 1990s the personal computer revolution turned into the social computer revolution. The thrill of having sophisticated computer power on your desktop turned out to be just the beginning, once your machine could connect to everyone else's via telephone lines. There is a global computer the size of humanity taking shape. Now that everybody can publish their own interests to a world audience on the Net, we learn irreversibly that the world is far stranger and more interesting that we would ever guess from magazines, books and broadcast media. Our sense of the world is altered and, oddly enough, in an optimistic direction. Two simple-seeming devices -- search engi