Foursquare doesn't have a revenue problem -- it has a user intent problem ]

"We are not a check-in app or a social app. We’re a shopping app. Everyone who’s using Shopkick is by definition interested in shopping. And that’s inherently monetizable" - Shopkick CEO Cyriac Roeding

Why has Shopkick taken off while people still doubt Foursquare’s model? Shopkick knows why it exists: to help you buy stuff.