Short story: Dude loses iPhone on local trails at some point during his three hour mountain bike ride; dude uses my MacBook (he's a PC owner) to activate his phone's "Lost Mode,"; dude recognizes blinking blue light, representing his phone's location on a map, is on COD, near Century Dr.; dude tromps around woods, using my iPhone's map as a guide, and soon finds his phone laying in the trail—in tact and working fine.
The app, called "Find My iPhone," is free. And as long as your devices are iCloud enabled (and running on iOS 6) the app can do lots of other neat things, like:
• Locate your iPhone, iPad, iPod touch, or Mac on a map
• Display a custom message on the screen
• Play a sound for two minutes at full volume (even if your device is set to silent)
• Remotely lock your device
• Remotely wipe your device to erase your personal data
• Lost Mode (iOS 6 or later)
• Driving directions to device location (iOS 6 or later)
• Battery charge indicator
Good use of technology.