Wasn't there some project about trying to find the independent bits of information among all the people in the world? So that if you answered a 33-question (2^33 is about 8.5 billion) true/false survey, your answers would be distinct from anyone else's.
Well I guess you could do it with longitude, latitude, and timestamp of birth, but I think it was supposed to be a personality survey.
However, he didn't propose a particular list of 33 questions whose answers are maximally statistically independent. Even with things that are totally uncorrelated, you do get some chance overlap where people happen to have the same answers on a small number of them.
For example, if we took the first 33 bits of the SHA256 of one's HN username, you and I happen to agree in positions 7, 8, 11, 13, 15, 17, 18, 19, 21, 26, 27, 28, 29, 31, and 32. (So we could say that each additional bit of that SHA256 value doesn't actually provide a full additional bit of distinguishing power relative to the previous ones.)
Well I guess you could do it with longitude, latitude, and timestamp of birth, but I think it was supposed to be a personality survey.