How best to market a crowdsourced product?

In the old days, companies developed products for their customers. The idea that the customer would have any role in the process beyond expressing a particular colour or flavour preference seemed unthinkable.
Henry Ford supposedly said that if he had asked people what they wanted, they would have said, a faster horse. Today, more and more companies have concluded that Ford was too pessimistic and that customers actually have a lot of imagination.