GIS software for analyzing MLS, rental markets?

[Aaron Knoll]

The RE world really needs a comprehensive visual analytics tool. 

I saw this, but it doesn't even come close to what *could* be done:

https://www.mashvisor.com

Can anyone think of a good way to scrape the MLS (both sale and rental), AirBnb, VRBO, and others? In fact, actual listings could (should) be anonymized: the tool would be mostly for investors and policymakers to understand long-term trends.

Who has thoughts on this? Where would one start?