I'm also a real estate broker. And a programmer. And a few other things ;-)

We looked at this exact market a bit. In the course of doing our research, we found a company with a similar (but better...or at least more functional) offering than the one you cite. And all of the sites are completely FREE for real estate agents. It's difficult to compete with a company that has a nice, easy-to-use system that is FREE. And they're just starting to market nationally. We eventually just started using them instead of developing our own...and we're a company with 50+ full-time developers on staff. I'd genuinely be interested in your ideas if you have a way to compete with free...