DEMO: http://tnmem.com:8084
Not included in the repo is a 100MB mysql database, but it is public data available on request. The main problem with the Shelby County data was the addresses. They had to be normalized to work with maps.
The project was done for The Commercial Appeal newspaper in Memphis, Tennessee, thus the look of the index.php with iframe. It might be done again in the future, but there is no 2013 project planned.
There is a little bit of everything: PHP, AJAX, jQUERY etc.
Notice the (Microsoft) maps with pins for the compared properties. If you click "Big Map" then change to aerial view, a shift-right-click on a house will attempt to fill in the address of the clicked-on house.