AT&T Mark the Spot is a free app that lets you help AT&T pinpoint problems with their network. If you have a dropped call, failed call, no coverage, data failure, or poor voice quality, the app uses your GPS location and makes it a snap for you to send AT&T an alert. (If you have a first-generation iPhone, it uses triangulation to pinpoint your location.) Of course, the question arises: if you have no service, how can the app send an alert? There's an option for marking your location and sending the info after the fact when you do have service. If you submit a report, AT&T sends an SMS acknowledgment. You also have the option of including comments. Read more about it in this article on CNet.