RakaatTracker

If you forget how many rakaat you have prayed, or what rakah you are in, Rakaat Tracker can help.

Simply hit the "Start" and put your iPhone into your front pants (trouser) pocket. If you have Alerts turned on, Rakaat Tracker will alert you in very sajdah. If you're in the first rakah it will buzz or beep once, and so on.

If you do not have Alerts turned on, you can check Rakaat Tracker after you complete your prayers. 

Just remember to put your iPhone on "vibrate" or turn the volume down so that you don't disturb others praying nearby.