The new iOS app "Cloak" combines location-based user data from Foursquare and Instagram, so you can actively avoid them. Cloak calls himself "incognito mode for real life" — something akin to the option of private surfing for the Chrome browser from Google. "You can think of it as the antisocial network," reads the app description in the Apple App Store.
After you start Cloak will give you a map filled with icons of the people you followit to Foursquare and Instagram, on the basis of the most recent places where they have zuccinis, or as marked on the location. When the mark people will appear within a block from you, you will receive an instant notification, and after 4 hours after last radar mark, their personal icon will fade assuming that they probably already left the place.