If you want to find your iPhone if it is lost or stolen, then iLocalis is for you. The iLocalis app runs in the background and periodically transmits your phone's location to the iLocalis server. If you lose your phone, you can find its location on a map, send a message to the person holding your phone, or make the phone call you so you can listen in on whomever has it.
Watch this video to learn how to install and register iLocalis. After installing it, change the Location services update rate setting to Every 60 minutes to decrease the drain on your battery. If you lose your phone, log in to the iLocalis web site and click Your iPhone. iLocalis shows you a map of your phone's current location, as well as links to its recent past locations.
Privacy concerns aside, it's fun to use the phone as a tracking device and trace your path throughought the day, and it's valuable to be able to locate your phone if you lose it.
This is an excellent tool. Don't forget to donate to Antonio to keep your iLocalis running after the initial free trial.