Ok here are a couple of apps I have been playing with for a couple of days:
they are both types of pedometers, the first one is MapMyWalk (free but ad driven) the app is a pay for service to get any what it claims is advanced feature (like using the app to access your music to listen to while walking via the app, call Go MVP! pricing is 5.99 per month). Overall the app is pretty slick it uses GPS abilities of your iOS device, the down side is battery usages suffers. it does have an ad free version that starts at $5.99 per month, $17.99 for 3 months or $ 12 months for 29.99. They also offer things like Runner, Go MVP bluetooth heart rate monitor plus a 1 year free subscription or a Cyclists, go MVP GPS bike computer with a 1 year free subscription.
The second one is Moves. Moves uses a different approach it counts the number of steps your are taking every time you move. It use the motion detection in iOS devices not GPS. The app is much more battery friendly (less draw on the battery), this is a iPhone app. Since I always have my iPhone on my person it work great for me. it does log your amount of walking so you can keep track of what you are doing daily. Moves currently is a free app in the iTunes app store.
Give either one a try let me know what you think.