Appealing to females who want to keep track of their menstrual cycles, Period Pace [FREE] is most definitely a top-contender. Why? Its easy-to-use interface and features that give you the best estimates make it an ideal application, especially considering it's absolutely free to download.
Coming from iPhone developer Aesop, who specializes in the making of applications appealing mostly to just-married couples, and helping with care of a newborn child, Period Pace certainly is the solution to tracking your periods.
You'll start by recording the day on which your period occurred, along with other information including symptoms that you experienced - after a few of these, the application will be able to predict when your next period will arrive thanks to its clever system, which calculates the date using all of the information received from the user.
The real beauty of the application, literally, is its great user-interface. The polished menus and such are solely enough to put the application beyond others of similar type. Additionally, the application itself is much easier to use than other utilities and similar healthcare applications. The application takes input from you with single clicks, and the few menus make it easy to navigate around the app. Plus, the application will display everything you need to know about your next period at the top at all times; things such as the actual date, your estimated next ovulation date and other figures are displayed making it simpler to track your period.
Had I turned out a girl, this probably would've come in great use for me. Currently, however, I can only imagine it being a great aid to women everywhere who need to check the date of their period. A quick visit to the application would let them know everything that they need to know, in a jiffy, rather than the application requiring multiple minutes to calculate the few important figures it efficiently displays.
For free, this is undoubtedly something you should download, men excluded.