apps for that

I just heard about apps they have for tracking menstral cycles as well as sexual activities etc.
Women can track their fertility cycle which can help them make better choices about their own actions and their own bodies.
I was always frustrated by the fact that my cycle did not "fit" the 28 day norm everyone talked about. Those times when I was paying attention it was about 31 days. In terms of trying to conceive or not conceive this was important information.
The app also tracks information you add about how you are feeling both physically and emotionally as you go through your cycle. It is really great to know these things so you can predict the days when you might not be the life of the party or become the bitch from hell if anything goes wrong that day.
Feeling bloated or anticipating the days when you might some midol on hand can be damned useful.
There is also a place to track sexual encounters and birth control used or not. 
Understanding our bodies at any age is a critical part of understanding our sexuality and can help us all make better decisions.