40 New Data Points In Google Analytics API - Analytics Blog | API's on the web | Scoop.it
From analytics.blogspot.fr - July 12, 2013 4:27 AM

Developers can use custom dimensions to send unique IDs into Google Analytics, and then use the core reporting API to retrieve these IDs along with other Google Analytics data.

For example, your content management system can pass a content ID as a custom dimension using the Google Analytics tracking code. Developers can then use the API to get a list of the most popular content by ID and display the list of most popular content on their website.