I would like to point your attention on this App: Photam

Photam is a photo-effect iPhone App that revamps the old Gotham filter by Instagram. The app provides additional features built around the «missing» filter: photam-feed, camera-filter and "serendipity" (Photam user of the day). A refined design we're proud of and deep integration with Instagram APIs.

Launched on the App Store on May 2013. You can get it at www.phot.am or watch the #photamfeed collected on our Tumblr http://photam.tumblr.com/