Plenty of social networking sites encourage this sort of behavior by giving users the illusion that they are merely interacting with friends, when in reality much of their behavior is viewable by any interested party. Google is another popular way of chec
J. Cheng, L. Adamic, P. Dow, J. Kleinberg, and J. Leskovec. Proceedings of the 23rd International Conference on World Wide Web, page 925--936. Republic and Canton of Geneva, Switzerland, International World Wide Web Conferences Steering Committee, (2014)
B. Ribeiro. Proceedings of the 23rd International Conference on World Wide Web, page 653--664. Republic and Canton of Geneva, Switzerland, International World Wide Web Conferences Steering Committee, (2014)