iTimes TimeTracker is a very easy to use time tracking tool for Apple's iPhone/iPod touch products. It is meant for all of us who need to report times spent on projects and project sub tasks.
Usage: Simply add items to iTimes TimeTracker and tap the "start" button on your current activity. iTimes starts to continously update the time spent on this activity.
If you have to switch to a different activity, tap "start" on the new activity. The old item is paused and can be reactivated at any time.
In case you have to report times spent on subtasks, you can very easily create a hierarchically ordered set of activity items. A started sub item automatically updates the total time of the parent item(s).
If you put a parent item on pause (e.g. via a switch to another item at the same level) an active sub item is automatically paused, too. This sub item is then displayed with status "yellow" instead of "red" because it wasn't stopped explicitly but indirectly because of the status change of its parent item. If you later restart the parent item, the previously active sub item timer is automatically restarted, too.