That's the idea behind iHound, an app that helps recover lost or stolen iPhones. Thanks to iOS 4's multitasking savvy, iHound automatically sends location data at regular intervals, thus allowing you to track the phone's whereabouts on the iHound Web site.
If that sounds familiar, it's because Apple's MobileMe service has a similar feature: Find My Phone. However, while MobileMe costs $99 annually, iHound costs $3.99.
That includes three months of tracking service; you can then extend your subscription by six months ($5.99), a year ($10.99), or two years ($19.99). Any way you slice it, it's way cheaper than MobileMe. And if you've ever experienced that sickening feeling of a misplaced phone, you know it's well worth the cost.
You can learn more about iHound over at iPhone Atlas, where a handsome and insightful writer gave the app a full shakedown. (Nepotism alert: it's me.)