Perhaps something like the website "Dollars" from the light novel/anime Durarara!! would be a good idea. One could go further than anonymity and create a website that's exclusive and send passwords to random people within a certain area: Los Angeles, New York, or London- big cities. Only people who know the password to the website would have access and since the website is exclusive to certain areas people would relate more to each other's topics. Rather than talking about international issues people could talk about things that are happening in the city. There would also be a sense of community knowing that most members are from the same area... Gah, I don't know. It has its limitations, but perhaps there's some potential in creating websites that are widely known, yet completely exclusive?