It's a good one, too. And simple. The question is this:
What is the coolest thing about your winery?
It is the answer to this question that drives your customers (and Web site visitors) to talk about your winery. Are you doing a good job of communicating it? If you are, you will hear it from other people (as in, "I think that X about your winery is really cool/neat/interesting/...").
Your Web site and/or blog is a great place to show and tell about all the cool things that set you apart from all the other people out there fermenting grape juice. And please don't obsess on the word "cool" - I might just have well as said "distinctive."
Obviously, great-tasting wine is one thing that sets you apart. But there are still lots of great-tasting wines out there. What is the story that people will tell other people?