For those who haven't heard of en_DK before, it's the "European English" (for want of a better description) locale.
It uses Commonwealth English (en_GB) for strings and ISO-14651-1 for collates. Dates are in YYYY-MM-DD, time is in 24h HH:MM format, Monday is the first day of the week, comma is the decimal separator, currency is euro and standard paper size is A4.
@erkin: The exact setting I use. Not all apps are translated into Danish, so when I use a regular all-round assortment on Linux, I just keep it in English... but yes, the standards can follow Danish. It is a very lovely option.