We market to friends very differently than we market to strangers. We do business differently as well.
Thanks to social networks and the amplification of stories online, we have far more friends per person than at any other time in human history. Nurturing your friends—protecting them and watching out for them—is an obligation, and it builds an asset at the same time.
(I want to distinguish friends from 'friendlies', the people you have a digital link to, but no real connection. Friendlies are basically strangers with a thumbnail of their face on your screen. They're not friends. And, while we're at it, the moment you treat a friend like a stranger (form mail, for example) they're not a friend any more, are they?)