Mark Rittman has a great post about "In Search Of Stupidity: 20 Years Of High-Tech Marketing Disasters". Mark is kind enough to recap one of the stories, here is a highlight:
Esber looked at the development community around DBase, and saw this as a missed opportunity for Ashton-Tate; every utility developed by a third party was revenue lost to Ashton-Tate, and every developer working with DBase was taking money out of Ashton-Tate's pockets. This was particularly significant as DBase had a very loyal development and partner community, and it was in fact these developers and companies that added to the DBase functionality that made it the number one database application on the PC platform. Esber then went on a one man crusade, threatening to sue anyone who worked as a developer delivering solutions using Dbase, together with third-party vendors who sold applications that were compatible with Dbase. At one point, Esber stood up at a software developers conference and shouted 'Make my day!' while threatening legal action against anyone who wrote DBase-compatible applications.