The Python Flickr API kit is a feature-rich Python interface to the Flickr API. It comes with a caching framework and remembers the user's authentication credentials automatically. It supports a variety of communication protocols, and offers different XML parsers to suit different platforms and preferences.
If you're looking to run a successful developer program, you should probably pay attention to Mathys van Abbe. He's the founder of Mobypicture (our Mobypicture API profile), which has just celebrated its 500th developer.
Apple's iOS Camera APIs make the iPhone a manual camera—for third party developers. Fleksy to be early out of the gate on iOS 8, but could use more APIs. Plus: Australian startup says it owns the "HealthKit" name, and Contract Logix a API integration.