FireChat (free) is one of the new generation of apps that lets you communicate to nearby iOS devices without Internet or mobile phone coverage. It shows you other people who are local to you, say on the same camping trip, and you can chat or share images using Apple's Multipeer Connectivity Framework, which can use WiFi or Bluetooth to connect two or more devices. You'll have to be able to run AirDrop to get it all to work, and that includes all iPhone 5 models, the fourth-generation iPad, the iPad mini, and fifth-generation iPod touch models. My older iPad would not work at all.
The app also lets you use standard Internet connectivity to participate in a running conversation with FireChat users anywhere in the world.
There are no logins or accounts required, and no setup. Everything is open, and that is the blessing and the curse of this app. You have no way to filter who contacts you, so at a venue like a basketball game you could be deluged with abuse. The range of the app is about 30 feet.