This work focuses on the analysis of online social networking services. We examine several formal definitions of various characteristics (numerical and structural) and introduce appropriate concepts, models and methods that could be useful for the analysis of information obtained from social networks. Preference analysis is proposed to be used to study interpersonal relations. Various modifications of Latané's dynamic social impact theory are proposed. The authors have studied techniques used to carry out psychological operations, and, as a result, have proposed several formal models. The paper briefly describes a software system that we have developed, which allows extracting, processing, analyzing and visualizing data from online social networking services. Our system has a data extraction module that can retrieve information from social networks such as Twitter, Facebook, and VKontakte.