Create Interactive Maps with Google's New Data Layers
Google provided a good use case in its official post introducing the Data Layer enhancement.
"Geographical data make maps interesting, informative and useful for users. For example, interactive Data Layers can be used to gather user opinions on the best places to visit and easily build heatmaps based on popular hotspots by using a Styling Function on the Data Layer. Or perhaps you could build a real estate site that allow users to draw Polygons to describe the areas that they do and don’t want to live in. The possibilities are endless."
In addition to graphical edits and the introduction of a GeoJSON editor, Google is also rolling the ability to display Line String and Polugon geometrics geodesically (their edges follow the curvature the Earth).