If it's presented as "We're building this product - tell us what you want it for" it would tend to select the people who are really keen. That's the kind you wa

If it's presented as "We're building this product - tell us what you want it for" it would tend to select the people who are really keen. That's the kind you want to start with - but you're right, it is a subset, probably a very small one. So maybe this is better for operationally getting started, rather than measuring market size. A related idea is to build less of the product, eg. the backend is run manually (ie. you are the backend). I like this one better, because it seems dishonest to me to say "buy our great app!" and then not have it. But I guess you can word it as a request for interest, like the HospitalVille example. Question: has Zyngna actually been successful with this technique? (I've only heard of Farmville).