Pregnancy Due Date & Fertility Calculator, Tools and Baby Kick App, by BabymedLLC
https://itunes.apple.com/us/app/pregnancy-due-date-fertility/id322948024?ls=1&mt=8
A powerful app that helps you predict ovulation or your due date. It also includes a kicking counter - even for twins - as well as a BMI calcultor to help you gain weight in a healthy way. The app is conceived by a real obgyn, Dr Amos Grunebaum. Free.
Clue
http://www.helloclue.com/
A beautifully designed, simple app that tracks your cycles and predicts when you'll ovulate, menstruate and have PMS, based on information that you log with one tap. A great app for any woman. Free.
What to Expect: Fertility
https://itunes.apple.com/us/app/period-fertility-tracker-from/id395980468?mt=8
The What to Expect series also offers this app with a personalised calendar that maps out your most fertile days. Also included are daily baby-making tips, access to the What to Expect message boards, and estimated due dates for each day you might conceive.
Fertility Friend
http://www.fertilityfriend.com
This website allows you to register and chart your cycles on their website, on your smart phone or tablet, for free. There is also a forum and other useful tools.