1. A method for predicting an opinion, the method comprising: building a corpus which includes a first collection of documents attributable to a first person and a second collection of documents identified from content in the first collection of documents; evaluating the corpus to build a model representing opinions of the first person relative to topics, concepts, or subjects discussed in the first and second collections of documents; receiving a request to predict an opinion of the first person regarding a topic; and generating a predicted opinion of the first person regarding the topic from the model.