My own[*] contribution in this area: A calendar with 12 months, each of exactly 30 days. Then the days between xmas and New Year (5 days most years, 6 in leap years) are struck off as "intercalary days"... they simply don't exist on the calendar, but just "happen". (I know, I know, people will name/number/label them anyway because some things still have to happen on those days, but <i>conceptually</i> they're non-working, non-accountable days.) Almost everybody takes a time-out during those days anyway (though maybe not so much in middle-eastern countries and a few other places -- I'd love to hear more about how those days work out in those parts of the world).<p>[*] Not my invention at all really, but that of the Maya people as one of their 3 interlocking calendar systems. Intercalary days were (iirc) counted as particularly ill-omened and unlucky and were faced with fear and trepidation.