Use this PHP library to interface with the App.net's Stream social networking API. Access application functions like: social graph, messaging, and places. Documentation, including code examples and access to other libraries is available on the library's GitHub page. Note that the API is in development and the library continues to be updated. The developers note that some updates may break backward compatibility for older versions.
PeopleBrowsr is another “noise to signal” processor of the social media tidal wave. The Research.ly platform they provide is impressive and engaging. I had to pry myself away from it. It is a tool to answer the question, "who in this social media landscape is relevant on this topic?" but that is just the beginning. The PeopleBrowsr API is a pay to play way to gain social media intelligence.