даты в календаре

Для венды есть WoCa (Female calendar) http://www.domsoft.net/index.php?r=11/14&s=1&lang=engl

Попробуй c wine.

>А еще было бы здорово, чтобы одновременно не один цикл мог рассчитывать

О, спулер любовниц - интересная идея :)

apt-cache show cycle

 helps to supervise the administration of hormonal contraceptive tablets.
 .
 Possibilities of the program:
   - Calculate days of menstruation, based on the length of the cycle or
     on statistics of previous periods.
   - Calculate days of "safe" sex, fertile period and day to ovulations.
   - Definition of D.O.B. (Date Of Birth) of a child
   - Allows to write notes.
   - Helps to supervise reception of hormonal contraceptive tablets.
   - Multiple users allowed. Data is protected by a password for every
     user.
 .
 NOTE: This program is not a reliable contraceptive method. It does
 neither help to prevent sexual transmision diseases like AIDS. It is
 just an electronic means of keeping track of some of your medical data
 and extract some statistical conclusions from them. You cannot consider
 this program as a substitute for your gynecologist in any way.
 .
  Homepage: http://cycle.sourceforge.net/

apt-cache show cycle

Description: calendar program for women
 Cycle is a calendar for women. Given a cycle length or statistics for
 several periods, it can calculate the days until menstruation, the days
 of "safe" sex, the fertile period, and the days to ovulations, and
 define the d.o.b. of a child. It allows the user to write notes and
 helps to supervise the administration of hormonal contraceptive tablets.
 .
 Possibilities of the program:
   - Calculate days of menstruation, based on the length of the cycle or
     on statistics of previous periods.
   - Calculate days of "safe" sex, fertile period and day to ovulations.
   - Definition of D.O.B. (Date Of Birth) of a child
   - Allows to write notes.
   - Helps to supervise reception of hormonal contraceptive tablets.
   - Multiple users allowed. Data is protected by a password for every
     user.
 .
 NOTE: This program is not a reliable contraceptive method. It does
 neither help to prevent sexual transmision diseases like AIDS. It is
 just an electronic means of keeping track of some of your medical data
 and extract some statistical conclusions from them. You cannot consider
 this program as a substitute for your gynecologist in any way.
 .
  Homepage: http://cycle.sourceforge.net/