The Intercom Node.js Sample Code by Intercom presents how to interact with the API. It provides requests and returns for client, company, contact, conversation, events, segments, tags, users, and visitors.
The focus of Gravity Rock Solid Recommendations is to help its business clients offer personalized recommendations to their customers. Their clients funnel lots of content, like video streaming sites, dating sites, Groupon imitators, classified sites and ad networks to consumers. The Gravity R&D API uses events to track user interactions. From there they import an item catalog to build user profiles to create the individualized recommendations.
Here is an interview with Scoreoid founder and CEO, Almog Koren. Scoreoid allows you to gamify apps using the Scoreoid API and backend as a service. With 3000+ games and almost 1.8 billion monthly sessions- this is one API startup that seems to be going places.