There are several apps for tracking your periods (and the moods and symptoms associated with it) but this one seems to be particuarly good. Sage is conducting a study on PMS and one of the participants in our study turned us on to it.
Here is a REVIEW by a woman iPhone user that I thought pretty much covered all the plusses and minuses of the app.
Also, you can check out Sage's PMS session if you are interested.
