A social networking system in which electronic business cards are traded as a format for social networking so as to provide for a better measure of social network relationships based on network significance and/or reputation score. Endorsement paths and/or card paths, resulting from trades, may be generated and visualized, and network significance and/or reputation score may be calculated at a given moment in time, or over a specific sub-network of users, such as by being calculated automatically at an interval of time or based on user action.