What is a common social interaction that Facebook simply does not provide right now?
Its the simple act of introducing two people you know to each other.
Sure, FB lets you suggest friends for your friends. But its (kind of) implicit that they are mutual or common friends already and you are just helping them find each other.
I have almost no single friends (right now) but I think a matchmaking FB app which lets you set up blind dates for your friends would be cool!
Update – I know Linkedin provides introductions as well as recommendations. I think most professional introductions are probably more like personalized recommendations that are only visible to the three people involved. So it makes sense to combine the two (call it an intro-commend) where you recommend someone professionally to someone else. Also something that Angie’s List could look into!