Private Property was a combination of individual scripts built in the mid-2000s. There were data crawlers that automatically gathered listings from all over the internet.
There were data formatters that automatically searched for property images on Google (allowed at the time) and generated a unique ad header, based on the information in the listing.
There were the blasters that blasted out theses re-formatted listings to over 10 free property classifieds - all linking back to a single website & blog.
This wasn't just an experiment. It yielded in an average of 30 emails/SMSes/calls a day from the resulting traffic. It was a near zero-cost, yet priceless real-estate marketing tool.
The ownership of the domain has been transferred but it still enjoys traffic from all my previous efforts. Some auto-blasted listings still exist today.