So ever wondered which friends show up on your facebook profile under your friends section ? Is it the orkut algo where the most recent friends who have logged in show up or is this completely random ?
It is incredibly difficult to know what algorithm facebook has intalled in order to display your friends but I remember someone from facebook gave a small talk at the Carnegie Mellon University last year. They said that generally the list of friends is random with the additional importance/bias to the people you are actually stalking ! (Simply put the number of times you check their profile , their recent activities and the likes) .
So basically every user activity at facebook is logged and hence manipulated in a manner than it suits the best on your profile. Stalking someone ? Facebook knows !