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.