Sure! It depends a lot on the product. But in our case, a key interaction was on Facebook. So we pretended to be doing market research on social media and brought a lot of people in for user tests. Eventually we'd have them log in to Facebook on our test computer, asking them what they though of various posts.

What they didn't know was that we used Greasemonkey to alter the Facebook page, inserting fake feed items using their real friends. (We told them at the end if they didn't figure it out.) Some people liked what we were doing, but a lot hated it. So many that it was clear we'd never get the market penetration we wanted.

My cofounder did a 5-minute video talk about it if you'd like more details. https://vimeo.com/24749599

As an aside, surveys are worse than useless for this. Look for things that let you understand live user reactions in circumstances that are as real as possible. Signups are a good metric, especially if they'll give you a credit card number up front. But if you can, always back the metric with live user tests and discussion with real users. If you're patient and ask good questions, you can learn a ton.