node-flickrapi is a library for implementing the Flickr API in Node.js. It comes with API method proxying and OAuth API key authentication, and its dependencies are the async, glob, open, progress, prompt, and request packages. node-flickrapi is released under the MIT License.
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.
Transloadit offers media upload, modification, and storage as a service for developers who need that functionality (or, as Transloadit's homepage puts it, "geeks who run web or mobile applications") but don't want to worry about it themselves. There aren't too many moving parts to it, but they're ones a lot of applications make use of. The Transloadit API's main functions include: file upload, image resizing, video file encoding, image thumbnail creations, and file storage on Amazon S3.
While map mashups are what have defined this genre of application, the second most popular type of web mashup here on ProgrammableWeb are photo mashups. How popular? Just this past week the number of photo-related mashups passed the 500 mark, and there are now 505 listed.