Hi

Ive got the Essential Baby Egg timer on my iphone. I actually thought to myself "Great- Im going to get pregnant with an iphone!" LOL

No really, its great because you can mark you AF, and put you cycle length and LPhase in the settings and it gives you an approximations on your fertile window.
I wouldn't believe it to be 100% accurate, more a guide, you even get a message as you come up to your peak fertility 'Go home now!'...(and DTD)....lol.

You will find though that is your cycles vary like mine youucan change the settings and it adjusts your fertile days but basically the general 'fertile week' is pretty close when comparing with your CM.

Anyhow, just a little bit on Apps.

Good luck
June