An innovative app for UNICEF does two things. One, it helps you get money you are owed back, without the awkwardness. And two, it lets you (and your friends) feel like they did something good today. Here's how it works: You open up the app, choose a friend who owes you cash and the amount and pick a UNICEF charity. The friend receives a message asking them to visit a microsite to "return" the money via PayPal.