The formatting of a stigmergic system landscape can easily be in the form of a geographic map. Real estate can be represented as agents, which provide relevant details of properties to let or for sale
Real estate agencies can create agents to represent properties (or even the property owners) by answering a questionnaire - which is then converted into an agent by the stigmergic system program. Similarly, people seeking properties in a particular area can create agents for themselves that can describe to sellers the type of property they are looking for.
Both buyers and sellers can visit the geographic areas of their choice to compare the details given by the relevant agents. It is a simple system that would allow easy search and rapid comparisons.
This application might be of particular interest to real estate agencies for either local or nation-wide coverage. It might also be an attractive feature on local information sites.