Meet four social networks bigger than Facebook (in some countries)[ Thu, 3 Jan 2013 20:49:52 GMT ]It seems Facebook's planetary ubiquity is inevitable ... until you take a look at the sheer size ofthose competitors: Total membership of the four major non-U.S. networks total 778 million.　Combine that with Twitter's 500 million active users around the globe, and you've got a social horde that eclipses Facebook's. Besides Twitter (whom you've no doubt met),　who are these plucky social networks standing firm outside the U.S.? Let's have a look.