Tim Ferris describes a similar idea in the Four-Hour Work Week, only a little more underhandedly - he has them fill in the order form, click the link as if to p

Tim Ferris describes a similar idea in the Four-Hour Work Week, only a little more underhandedly - he has them fill in the order form, click the link as if to proceed to the payment page, only to present them with a page saying "Sorry, due to unexpected demand, we can't take your order right now." The customer believes that they are actually buying something, when they're actually just filling in a survey. Like I say, it's underhanded, but at least you can have a little more faith in the results.