That’s how PMSBuddy.com pitches itself. To wit:
PMSBuddy.com is a free service created with a single goal in mind: to keep you aware of when your wife, girlfriend, mother, sister, daughter, or any other women in your life are closing in on “that time of the month” – when things can get intense for what may seem to be no reason at all.
Note that they are smart enough to not include “employees” in the list of women to keep an eye on.
Is there anything the internet can’t do?
(Hat tip: Greg Feldman)
and 
. You can also watch it on 
There is a site for women to track their own cycles. Mon.thly.info has an algorithm that will track (and then predict) women’s menstrual cycles. It includes features like a reminder a day or two before, and an estimate of where in the cycle you are (good for planning conception). Additionally it is significantly less offensive.
Wow, how offensive is that. And creepy. I don’t inform my father or brothers (much less my non-existent SONS) about my menstrual cycle, thank you.
Otherwise known as a “calendar.”
I cannot believe that such a site is advertised here on Freakonomics. What is its relation to Economics?
I’m not sure I really understand the point of the site. If a woman in your life is irritable, you should find out what’s bothering her by discussing it, not by making assumptions because some website emailed you saying “it’s that time of month againnnnnnnn.”
That could prove to be a very useful tool if it sends you a warning ahead of time, for a variety of reasons.
BH- Oh, I think after a few years people can usually tell. I had a boyfriend once walk in the door,look at my expression and say “Oops, I should have checked the calendar”.
Hey, I wouldn’t mind having certain people know when I’m REALLY not in the mood to be bothered.
“Coworker”, “Secretary”, “Employee”, and “Boss” are included in relationships you can track. Guess they aren’t as subtle once you sign up.