"Hang the fan 8 to 9 feet above the floor so no one is decapitated."
-from a short article in the Olympian about how to install a ceiling fan.
UPDATE: Alert reader (and blogger) Kris Tefft was reminded of a Mythbusters episode that tested this very threat. Conclusion: "Unsurprisingly (if you've ever put your hand up into a ceiling fan), the household fan did nothing to the dummy head."
But, of course, your mileage may vary.