Yes, in the USA: MM/DD/YYYY is also common. However just like DD.MM.YYYY, there may not be leading zero'es for the days or months.
I prefer one of the 12 formats shown in my previous post so that an ASCII sort order will work. Converting a date to a numeric value for comparisons will work and I don't have any big quibble with that. But I would run a regex to convert: DD.MM.YYYY to YYYY-MM-DD for storage and processing purposes.
Wenn der Benutzer ein Deutscher ist, würde ich die Ziffernreihenfolge für Anzeigezwecke ändern. Or maybe not? My German is not that great!
Update:
I use YYYY-MM-DD as expressed in GMT/UTC time zone for all of my logging. If some conversion to local time formats for a user display is necessary, I do that. However almost all of my work is in GMT/UTC. Yes there is a small technical difference between these two definitions of time. For my work, this difference just doesn't matter. Some DB's use a numeric value for the date and some use a string. Any DB that uses a numeric value for a date, has a function to generate that numeric value from YYYY-MM-DD.
I use the terms GMT and UTC interchangeably. See Coordinated Universal Time. This wiki article notwithstanding, I recollect that there is some extremely small difference having to do with small fractions of seconds related to this "leap second" stuff. Nobody here has to worry about UTC vs GMT => for all practical purposes, they are the same.
