Pedometer Step Counter is an app that lets you keep track of how many steps you take and calories you burn. The steps are counted using the motion sensor, not the GPS, so it won't consume too much battery.

The app runs in the background at all times as you walk around. Obviously you can stop the app at any time if you no longer want to count your steps or even restart the count. You can also set specific objectives and get medals as you take more and more steps. From the main menu in Pedometer Step Counter you can view a complete chart showing all the steps you take in a day.