is a local site that provides comprehensive real estate information. I think it provides a great service and is an example of a software product that really solves a customer problem. I mentioned it during the GUI meetup tonight
You can find information on basically any house, condo, etc., sort it in a variety of different ways and even get email alerts when new properties that match your criteria come online. It is amazingly comprehensive. For instance, I have been using it to track number of condos per day whose asking price is dropping. Average has increased from low teens per day in the fall to about 30 per day recently - a strong sign that price declines are accelerating.
In any event, it's a great business too. This profile
explains the background of the site. Though the site is free, leads from it helped him generate real estate sales of $25 million dollars. That's a nice return on his investment in building software.