The official Google Picasa client libraries help to write applications with the Picasa Web Albums Data API. Users can upload and share photos on Google+, tag friends, and filter images. Picasa is available for download.
DropBox recently sat down with Gordon Wintrob over at getputpost.io to reveal how they built their APIs from primitive beginnings to handling over 500 billion calls a year. The Dropbox API lets you work with files, do full-text search and manage file and folder sharing.
Flickr has announced the release of two new Flickr API methods. The new methods are related to what are known as the Flickr Pandas, an experimental service where several virtual pandas select safe, public Flickr photos they consider interesting, or photos which have been geotagged.