Web/Android/iOS: Human trafficking is a massive, global problem -- one that an app alone won't solve, but one that this app may be able to help with, just a little bit. TraffickCam asks you to snap pictures of your hotel room, creating a database that can be matched to rooms in photos with trafficking victims.
The app's description describes this more aptly than I possibly could:
Traffickers regularly post photographs of their victims posed in hotel rooms for online advertisements. These photographs are evidence that can be used to find and prosecute the perpetrators of these crimes. In order to use these photos, however, investigators must be able to determine where the photos were taken.
The purpose of TraffickCam is to create a database of hotel room images that an investigator can efficiently search, in order to find other images that were taken in the same location as an image that is part of an investigation.
In short, by snapping a few photos of your hotel room wherever you stay when you travel, and then identifying that hotel room, you give investigators another clue into where photos they find of trafficking victims may have been taken, and if they know when, it can be a matter of narrowing down who stayed where at what time. The app is a project of the Exchange Initiative, an organisation dedicated to ending human trafficking around the world, and offering real resources to help do so.
TraffickCam is available for free (of course), for iPhone and Android, and there's a webapp if you'd rather not install anything. A few reviewers in iTunes and at Google Play note (rightfully) that the app and its database is only as good as the law enforcement agencies using it, and the fact that you do have to be in the hotel room in question when you take and upload the photos makes them worry this is a setup of some kind. The developers try to put some of that to rest in their FAQ, although they don't specify which law enforcement agencies they allow to access their database. For more, hit the links below.
TraffickCam (Free) [iTunes App Store]
TraffickCam (Free) [Google Play]