They’ve just experienced your awesomeness, and they’re primed to talk. You just need to put something in their hands to help them do it.
It doesn’t have to be fancy or expensive. Just something simple and visual. Take the example Austin thrift store Uncommon Objects. They keep a big basket of fans next to the register with a giant sign that says “FREE” next to them.
The result is hundreds of people walking around the South Congress shopping district, carrying small ads for Uncommon Objects into every store and restaurant they go.