Tracking your fertility with an app for your phone makes it incredibly easy. Each app has a slightly different take on what it tracks and how the information is presented in a variety of ways. This allows you to find just the right app for your fertility tracking needs.
This is a free menstrual calendar tracker. It is made by the folks over at FeritilityFriend. Here you can track your cycles, symptoms, and dates of intercourse. It has a password protect ability on it. There is also a helpful hint of the day and you have advanced options to sync this with your profile. This is a free app.
Another free way to keep track of your period on your iPhone. This app is handy and has clanedar and list views. You can track the days of your cycle as well as symptoms. There are visual cues for things like breast exam reminders and days that you are likely to be having yoru period. There is a fee version as well called iPeriod Ultimate.