Week Number ISO by MOB - This program converts between dates and week numbers (ISO) and day of week. More functions: adding days, adding business days (i.e. only counting m-f), day count down to certain date (timer), moving holidays (some are unique to Sweden, such as Midsummer's Eve). However, the program is in English.
The program is very flexible and you will hopefully be positively surprised at how many problems can be solved using it. E.g. you can on most devices copy the numbers to the clipboard. It handles both positive and negative numbers when adding days or showing the timer days left.
The MIDP-2.0 version has an additional feature. When you add days you can enter a degree of e.g. a part-time job after a decimal-point. E.g. 100.75 means add 100 days with a non consumption rate of days of 75 %. I.e. it would add 400 days. This can be used to e.g. compute the last day of an unemployment insurance, and in this case you should add business days.
This program "Week # ISO" is Copyright 2007 by Mikael O. Bonnier, Lund, Sweden <email@example.com>. All rights reserved. This program is free software licensed under the terms of "GNU General Public License". Donations are welcome. The source code is at <http://www.df.lth.se/~mikaelb/wap/>.