FREE means FREE. There are no costs to get your house listed, view house referrers, upload photos tracking ads, filter requests from buyers etc. We want you to post your house online and welcome any feedback to improve on your needs.
The Unique URL takes visitors directly to your house listing. Use it to post in your online and offline advertisments. Send the link to friends and family, put it on your blog, email signature.
Post and track your house details on third party websites like Craigslist.org
Keep track your of post history and then review the incoming links/visitors that came from specific sites, newspapers and magazines.