NYANKS on 18 February 2011
A killer application (commonly shortened to killer app), in the jargon of technologists, has been used to refer to any computer program that is so necessary or desirable that it proves the core value of some larger technology, such as computer hardware, gaming console, software, or an operating system. A killer app can substantially increase sales of the platform on which it runs. (Wikipedia)
All up to interpretation.
