I like the idea of Zillow comments and guessing sale price though. It should be possible to comment on any web page.
I plugged in my house just to see. It's all public info anyway... it couldn't find the construction year (public), renovation year (public permits), recent sales (public), it called my taxes high (wrong), it considered _all_ of Brooklyn for price comparables (wrong), ...
I initially had only the comments and price predictions, then added the analysis around it. I need to add more discoverability for comments to pick up though.