It is commonly used to create more subtle reflections such as on wet floor surfaces or in puddles.
Floor reflection unity.
More info see in glossary window that are used for editing the size and probe origin properties directly within the scene.
You can probably use this for more things like wall mirrors and multiple reflections in the same scene but that would require quite a bit more scripting magic.
I suspect that this will be the hardest part of what you need to accomplish.
This approach is very hacky but you can use the new reflection probes in unity 5 to easily create realtime reflections for something like a reflective floor.
Now i did realize that unity free has reflection probes.
There are two buttons at the top of the reflection probe inspector a unity window that displays information about the currently selected gameobject asset or project settings alowing you to inspect and edit the values.
From my understanding you create a material push the smoothness to 1 and then place a reflection probe in the scene and all the materials smooth enough.
I can t wrap my head around how do you make a floor that reflect the environment and just the floor.
With the leftmost button size selected.
I like this opencv asset for unity.
It may be possible to get some sort of sensors in the floor and then you re doing entirely custom things to read the data.
More likely you d use a camera in the ceiling and probably want to process it with opencv.