This app displays the current week number in English, Norwegian, Swedish and Danish.
It also allows you to import the week numbers to you main iPhone calendar.
This little app displays the current number of the week, and also calculates the number of the week for any date in the past and in the future. It uses the ISO method, where the first day of the week is on Monday.
The app displays current week number on the icon badge, so that you have the current week number easily in hand when you need it.