Has anyone tried using a survey to generate leads and to do market research?

I've heard some internet marketers using a "probe campaign" to determine the needs/wants of a market. They create a simple site saying they are creating a new book about tea and to make sure they don't leave anything out, tell me your biggest question about tea. Then they give them a free copy of the book when it's done.

Using this method, you get the email address and enough questions to make a book.

How about for offline? Drive traffic via direct mail or space ads to an online survey. Get the contact info and ask them questions about their most pressing problem. Give them a free widget for filling out the survey. Take the replies and build a product targeted to the market.

Of course, you would niche this to a specific market to narrow the audience.

Any thoughts?

MikeC