More Friends 5

This one is actually pretty useful.  The More Friends app charts which of your second degree friends show up the most times.  For example, if 10 of my friends are friends with somebody on FB, there's a good chance that I know them too.  It gets a little distorted by Internet celebrity types (five of my friends are friends with Arianna Huffington!), but overall it's a cool app, and a good example of feature arbitrage.