Venmo
Venmo is a social payment app and service that makes it fun and easy to pay friends on the go. Venmo works via SMS messages, mobile iPhone and Android apps, or the Web. Users can leave notes and comments, push their payments to Venmo’s social network and/or to Twitter, foursquare and Facebook.
While I find it a bit weird that your friends on social media are aware of the transactions between you and your friends, I love that Venmo makes it easy to pay your friends. Out to dinner and they take cash only? Allow your friend who always carries cash to pay, but before you make it back home, you can make sure that there’s no debts between you and your friend.