TextPride was a fine business, but a tiny one. Meanwhile, the market for messaging apps was exploding. Facebook FB 0.61% bought WhatsApp for $19 billion; that service now has 700 million monthly active users. Tango, an app with 250 million registered users, is worth $1.5 billion. Kik has 200 million registered users. Snapchat, worth $10 billion, has 100 million users. A new study, commissioned by Kik, shows that U.S. users now spend more time on average in messaging apps than they do on social networking apps. The only problem? These messaging apps need ways to make money, and there’s no reasonable way for advertisers to wedge themselves into conversations between friends.