Instagram is a very useful and enjoyable app. I should know given my addiction to it and following others and their photos. It is a quite restrictive app, however. One such problem is the inability to private message other Instagram users. Fortunately, there's an app that fixes that problem.
InstaDM offers a full featured chat client all through the Instagram API. Users can chat privately to their heart's content with contact lists of users' favorites possible as well as push notifications. It's an ideal way to chat to friends and to make some new ones, thanks to the ability to search for any user from within the app.
Everything is shown in an attractive and familiar fashion, much like when SMSing someone from an iOS device. InstaDM is an ideal accompaniment for the regular Instagram user, adding a much needed way of socializing with people on the network.
InstaDM is out now and it's free to download.