Engineering standard is year-month-day
The reason we do that is because putting dates as year-month-day means that their chronological and alphabetical order are exactly the same. All of my work time sheets are named year-month-day and that makes it easy to sort them in databases, excel, windows explorer, whatever. Today is 2011-08-22. All of the same year is grouped together, then all of the same month in that year are grouped together. Perfect.
If you want to turn your computer filing system into a total clusterfuck, all you need to do is put the dates in any other order. Instead of grouping the years together, you might end up growing all days 03 together so the list shows January 03, then Feb 03, then March 03 in that order. Maybe put the month first so it groups January 2005 and January 2006 next to each other but February 2005 is page over.
The absolute worst I've ever seen of any file system was when some retard put it month first and spelled it out. The months didn't even go in the correct order. February normally comes after January, but F is before J in the alphabet, so it would list February before January! Holy jesus. I hated that job so much.