[W/K] :: killer app

  killer appThe application that actually makes a sustaining market for a
     promising but under-utilized technology. First used in the mid-1980s to
     describe Lotus 1-2-3 once it became evident that demand for that product
     had been the major driver of the early business market for IBM PCs. The
     term was then restrospectively applied to VisiCalc, which had played a
     similar role in the success of the Apple II. After 1994 it became
     commonplace to describe the World Wide Web as the Internet's killer app.
     One of the standard questions asked about each new personal-computer
     technology as it emerges has become "what's the killer app?"