The May issue of CACM has a nice essay by Peter Denning. He denigrates the view of scientific research as input to human knowledge, with teaching as an output function. Instead, he espouses research and publication as a process of convincing the community that a new fact is true and usable, with teaching being the training of others to participate effectively in this process. As a corollary, Denning sees little merit in measuring scientific contribution by publications and citations. Impact on society can be through "seminars, symposia, professional meetings, laboratory visits, ..., writing articles, press releases, the electronic networks, and more." And through training of students. (If you take that view, though, don't forget to convince your tenure committee.)