My girlfriend recently received one of those abominable excel spreadsheets from the legions of those bored at work. It asks your birthdate and then lists your age in a variety of units, along with some positive traits of your zodiac sign.
I started wondering about excel and how it got to be so unbiquitous, and then I noticed that the figures are wrong. In one spot it said so many days, yet your age is listed as many more weeks - on the order of 7 times more. Guessing they were just mixed around I did a few calendrical calculations with some trusty Perl modules and found that the figure given for days was around the right number (but significantly out) and the number of weeks was in fact the number of 1/7th day parts, and *ugh*.
So, I started on a simple web app that could render these spreadsheets utterly deprecated. I called it Tempus Fugit.