instaDM (iOS) app for $0.99
If you're like me, at least once you've wanted to start a private conversation with another instagramer, clicked every button on the interface and couldn't find how. Why? because it's not possible. But don't worry. instaDM allows you to chat privately with other instagram users. A full featured chat client that works out of the box (or App Store should I say?) with your instagr.am username and password. You can start chatting with any user on instaDM in less than 1 minute.