Ed Felten tells the interesting story of a nameless computer scientist who's developed something useful, but... Well, I'll let Ed pick up the story:

He isn't sure he wants the public to find out about his research. He says this, even though his work would probably be of interest to many people, and could be useful to far more. The problem, he told me, is that if too many people find out what he has done and realize its value, some of them may start using it for illegal purposes. He doesn't want that kind of trouble.