There are 100 million people around the world using Facebook. This number is from the official Facebook blog. They don't mention the number of active users. But it is safe to say that they are a lot.
I will describe an evil idea to control the decisions of a great number people that doesn't involve any intrusion on their privacy. They will be oblivious to this interference.
It is wrong to think that following your friends online will introduce you to new ideas, opportunities and information. However, if you spend the same amount of time reading other people ideas but following a certain topic that interest you. This will probably expose you to more information, viewpoints, ideas, etc..