  We describe our work in the collection and analysis of massive data
describing the connections between participants to online social networks.
Alternative approaches to social network data collection are defined and
evaluated in practice, against the popular Facebook Web site. Thanks to our
ad-hoc, privacy-compliant crawlers, two large samples, comprising millions of
connections, have been collected; the data is anonymous and organized as an
undirected graph. We describe a set of tools that we developed to analyze
specific properties of such social-network graphs, i.e., among others, degree
distribution, centrality measures, scaling laws and distribution of friendship.
