Recently, I installed the 'add a friend' thinking that if I can get them on my friends list on facebook I can keep them in the loop and market to them more effectively. Well, this worked out pretty well I have to say, 1 day after installing the module I got 36 friend requests. I created a new friend list and added them to it, now I plan to promote new products/articles to them via FB.
The module gave me a great way to connect & market to people. Only thing I would want is more default button images, but then again I have the option to upload my own custom buttons.