Google has opened their Cloud Vision API. When backed by their Machine Vision infrastructure, this API enables developer to give their applications vision capability. This article gives a high level overview of the API and a short tutorial for building an application that uses Google Cloud Vision.
Gravatar is an attempt to allow users to have one globally recognized avatar. The service, around for several years, allows a user can set an image as an avatar and have it recognized on a variety of sites. Later, users can change an avatar once and have it change on every Gravatar-enabled site that they use. Though the service is somewhat well known, what is not is its robust API for developers to integrate the Gravatar service into their own sites.