This great article from Forbes makes the point that in the new world of social media your customers remain buyers, all the time.

“Customer” is an artificial label for counting and segregating buyers that have purchased your product.  The notion of “customer lock-in” is, in today’s world, a myth. Customers don’t stop evaluating their purchases or their vendors just because they bought. It’s actually the opposite; buyers are always buying even when they’ve just bought”.

Social media can help to find out what the buyers are saying and feeling.

http://www.forbes.com/sites/christinecrandell/2011/10/08/the-gold-in-social-customer-service/