Domain squatting for competitive intelligence
Competitive intelligence is full of slightly crazy ways of collecting information. Analysts tend to be people who love data and analysis, and often enjoy the chase for its own sake. Even methods that are too ineffective or too illegal to be used, are nonetheless intellectually appealing.
One such method is domain squatting...with a novel purpose. This 2008 IT World article talks about a possible case of misspelled domains being registered, and only their MX records set up. That makes the domain capable of receiving email, but not of being a proper website. The purpose is to catch emails that are sent to that company where the domain part of the email address has been spelled wrongly. So, to email@example.com, for example.
Of course, the chances of receiving some useful competitive intelligence are microscopic, not to mention that this is probably illegal. But the lengths that people will go to, eh.