Facebook started out as a fun way for friends and family to stay in touch with one another, but over the years it has devolved into a place where the random people you meet can go to confirm said meeting.
And if you stay on Facebook long enough your friends list will look more like a gallery full of names and faces you vaguely remember from some point in your life.
Or, if your experience is anything like the sister in this strip from Pigminted Comics, your Facebook friends list will remind you of all the places you've been!
-Via Geeks Are Sexy
I used to do Friendster, and I make sure only accept friend requests from people who I know real well IRL. Yet even then there are those who asks and accepts any and all requests even from strangers just to inflate their friends numbers. I just don't understand that. If I'm declaring on the internet that Joe Shmoe is a friend, he'd better be one either in meatspace or in cyberspace.