Losing a phone isn't cool, but getting it back sure would be. The person who lifts someone's smartphone better pray it doesn't have Prey Anti Theft, a tracking and security tool for Android and for iPhone and iPad that also protects Mac and Windows PCs. Prey uses GPS and Wi-FI to track device location and once put into action by any of three registered devices, sends an email with a web link with the phone's location pinned on a map. The free version includes 10 such tracking reports, and can turn on Wi-Fi and/or mobile data, remotely trigger a factor reset (erasing all data), get a snapshot of the phone's current user, and even detect and send an email if the SIM card is changed. A Pro edition starts at $5 a month and adds batch installers, priority support and unlimited reports per device.