Venmo

When money and friendship mix, the results can get awkward: You front a friend some cash, and then what? Venmo, an app that helps you exchange money through mobile devices, is designed to remove that awkwardness and replace it with something social, and even fun.

Pay 555-555-1234 $13.70 for dinner. It seems simple; sending money to a friend or business with your phone, but after years of trying, the practice never really caught on in the U.S. Past attempts at sending money with a cell phone have been simple enough to use, but the fees involved often...