Twice a year as I set my clocks for daylight savings I wonder "isn't it the future yet? Can't computers do this for me?" Then I remember the complexity that is the unix timezone database. 444k of datafiles (260k without comments) containing facts like "Louisville, KY didn't observe daylight savings time in 1974."
This spring, daylight savings time changes at 45 different times around the world. No wonder it's so hard to know what time it is.