The Klout PHP SDK by Rob Bertholf integrates analytics into applications, useful to understand reputation based on sentiment features. Methods allow to lookup by id & name in addition to access user score & influence.
Well over 600,000 developers participate in a topcoder community that not only allows them to expand their development skills, but also gives them access to projects where they can get paid for participating.
The Twitter API has taken a winding road since its initial launch in 2006. Since 2012, Twitter has continued to clamp down on API consumption and usage, often to the dismay of the developer community. However, Twitter continues to understand the value of API features to its growth and the developer community.