phpFlickr is a wrapper that allows developers to easily integrate the Flickr API's functions into their PHP applications. The wrapper covers functions for authentication, caching, uploading photos, and replacing photos.
Flickr has added more real-time goodness to their photo API. Using a publish / subscribe (PubSub) system, developers can now receive real-time updates across millions of photos across Flickr friends, Flickr Commons, and by tags and geo-location using the Flickr Real-Time API.
Venueseen, a visual marketing and social media management solutions company, has just announced the release of the Venueseen Campaigns API allowing developers access to a powerful Instagram driven marketing tool.
Skybiometry's cloud-based face detection API serves as a drop-in replacement for face.com's API. This REST-based API can be used in combination with almost any programming language, making it possible to integrate with any device that has internet connectivity.