@Photowebmax and @noahlearner hit the nail with their remarks re: MLS (Multiple Listing Service).
For those who may not know, most real estate agents work for a broker who is affiliated with one of the larger brandname agencies, eg: Century21, Keller Williams, etc. These agencies usually offer their agents linkage to some local MLS database. More than likely, your real estate client will want to have his/her website link to this MLS so web visitors can search available properties based on any criteria they choose.
At the same time, your client may wish to "feature" specific properties. These may be "exclusive" listings by only your client (or his/her broker), or they may be just properties in the MLS that the agent wants to showcase.
There are a multitude of ways to handle featured properties in modx: tvs, individual pages, ditto, etc. Your choice will depend on how many properties, frequency of updates, and how you connect to the MLS feed, limited by what that feed offers in way of online connections: iframes, xml, etc.
In this modx example (
http://www.bozemanmontanarealty.com/), my client offers the MLS "search" tool as a simple iframe. But he also wanted a column on each page that featured three properties that he chose from the MLS. We set up this column as tv that he controls, and each property links to the MLS for the property "detail" page.