We divide potential NII (National Information Infrastructure) services into five broad areas: Collaboration and televirtuality; InfoVISiON (Information, Video, Imagery, and Simulation on Demand), and digital libraries; commerce; metacomputing; WebTop productivity services. The latter denotes the broad suite of tools we expect to be offered on the Web in a general environment we term WebWindous. We review current and future World Wide Web technologies, which could underlie these services. In particular we suggest an integration framework WebWork for high performance (parallel and distributed) computing and the NII. We point out that pervasive WebWork and WebWindows technologies will enable, facilitate and substantially accelerate such complex software processes on the NII. We briefly analyze seven broad application areas: society; business enterprises; health care; defense command and control, and crisis management; education; collaboratory; manufacturing. We contrast their use of NII services with a more detailed examination of the manufacture of complex systems, such as aircraft and automobiles. This application stresses the NII but there is a remarkable opportunity to develop new manufacturing practices that offer cost savings and reduced time to market.