So I was just measuring the latitude and longitude of my new house (closing in three days!) to play around with solar heating ideas -- when I noticed how close to 40 degrees of latitude it really is. Just a shade further north, and it would be right smack on it.
So I panned north a little, then a little west... My Dad's chicken house is precisely at 40.0000 degrees latitude. My old bedroom is at 39.9997, if you were wondering. The chicken house's longitude (and that of my bedroom) is 85.1561 degrees, not nearly as interesting a number.
Fascinating. I hadn't really ever considered how small a distance one ten-thousandth of a degree of latitude might be, but it seems to be about ten or fifteen feet.