FullContact - PersonPrivate API
The FullContact Person API takes a piece of contact information, such as an email address, and adds information such as name, job title, and social profile data from more than 120 different social networks - including Facebook, Twitter, LinkedIn, and more. It then returns the enhanced information in XML, JSON, or vCard format. You will need a FullContact API key in order to use this service. It's free to try - to sign up for a key, please visit https://www.fullcontact.com/developer.