We're facing nowadays a enormous boom of any kind of online communities, ranging from the typical ones of contacts and dating services (normally making money by subscription methods) to professional ones (e.g. LinkedIn) or friendship ones (e.g. Facebook). I tried myself several of these communities and you realize that it becomes annoying having to sign in for every different interface. Finally you end up choosing the ones with the most appealing interface, the ones where most of your friends/contacts are, etc.
But when you loot at the amounts paid for some of those projects and the ones that are being at stake for the buyout of companies like Facebook, that makes us think at first hand about the "bubble burst" of 2000. Are they really profitable? Their model is subsidizing users (the only way to attract thousands of them everyday), and their main revenue is (again) advertising. But the power that lays behind them is their biggest asset: the number of customers that are using their services 'loyally'. If we imagine the amount of potential customers and the amount of data that they have from them (those non-confidential), we can easily realize their capabilities.
There are also theories that explain that any person in the world can contact any other person by six degrees of separation (six persons that know one or tow members of the chain till reaching the other side of the link). In the end that is leveraging the advantages of socialization, networking and the needs of people to communicate in a global world!
