In the wake of a landmark court decision, traditional real estate brokerages are playing catch-up with online startups that have been developing tools to display

What datasets do real estate agents/brokerages deal with in their business and how do they manage it?

I developed a full dataset on properties a while ago but it turned out to be to expensive to maintain.  It included:
County Assesors information
County Recorders information
Notices of Default
Notices of Sale
Preliminary Title Reports (from multiple agencies)
Public Domain Reports
Legal News Reports
In addition to current status, the reports covered history in a number of the above categories.  The info was live, available online and fully formatted for mobile – IMHO it was way ahead of its time.