MIT Media Lab’s Playful Systems group have developed an app called 20 Day Stranger that pairs two people from opposite sides of the earth together for twenty days. Without divulging the name of the person you're paired with, the app updates you with details of their day as it happens in real time. It's like Chatroulette, except with way less inappropriate nudity.
When they wake up, where they walk to, when they're driving, and even the weather around them — 20 Day Stranger gives you a window into someone else's day to day life. By utilizing the iPhone's GPS features, the person on each end of the world has to do very little to signal when their activities start and stop.