Edit:
Very important change you need to make to your privacy setting:
go on privacy click on news feed and wall, click on actions on external websites and select Don't allow any websites to post stories to my profile.
Pretty soon you'll be recieving advertisements from your friends, say warner brothers wants to advertise the dark knight, they'll pay facebook a decent amount of money for an advertisement. Facebook then takes over a friends account and sends you a message on your wall that says "I totally loved the dark knight you should go see it"
I dont know about you but this strikes me as an extremely dodgy buisness practice that facebook will be employing very soon.
Facebook are losers
This is based on the idea that we dont listen to advertisments and prefer to listen to our friends so their just going to skip pursauding and pretend to be our mates.