As for social networking sites I have used facebook, orkut and linkedin. I am more active on facebook. First, I used orkut, but then I realized that facebook was much easier and almost all of my friends were registered on it. I really don’t know why other social networking sites are not so widespread. I just remember that when I used to tell my friends register in orkut they seemed reluctant, but all of them are very happy to be on facebook. I guess the navigation is much easier on this site and the community is bigger. I still keep my Linkedin account as I understand it is a professional network and I might need it one day, but I feel I have not explored it that much.