iBeenThere! app for iPhone and iPad

Monitors your location in the background and detects when you make a stop.
Notifies your friends with push notifications allowing them too see where youve been.
You can add friends (other users of the app) from your Address Book or by typing their apple id in the search field.
Each friend can be given individual permission to follow.
Play/Pause button enables and disables location monitoring.
App is using your iCloud account to store visit information, and allow other users to find you. iCloud account is required.
Continued use of GPS running in the background can dramatically decrease battery life.