Such as Pluterday and the real estate effects of psychic dead zones. I’m not talking about Ringworlds or other well known Big Ideas, I’m talking about lesser known ideas that are nonetheless cool.
For example, in “Where Were You Last Pluterday” by Paul van Herck, a regular schlub discovers that rich people have something poor people do not even know about: Pluterday, an extra day of the week they have all to themselves. No lines at the ski lifts, tables in all the best restaurants to be had by walking in, deserted beaches where crowds normally fill the sands, etc. etc. It’s a thought-provoking and funny idea, my wife and I still laugh about it when we tootle about when the streets are empty at unusual times, like when the Bulldogs and Yellow Jackets are both playing home games.
On a more subtle note, there’s “Highways In Hiding” by George O. Smith, set in a future in which the Rhine Institute has figured out how telepathy and remote sensing (the ability to psychically see objects hidden by walls, etc.) work. Turns out these two psychic powers are common, almost everybody has them, some more than others, but with training they manifest to various degrees. Plus both senses can be exercised over a range of thousands of yards. There are also naturally occurring “dead zones” where the psychic powers don’t work, also not rare.
Now here’s the nifty subtlety: the real estate market is knocked for a loop because some of the dead zones are in places where ghettos and other substandard places once were. They’re now highly valuable real estate, because no one wants to live in a place where just anyone who drives by can read their minds or sense what they are up to. And of course once-valuable real estate has gone down in price for the same reason.
Now that’s thinking it through!
Any other original and nifty ideas or nice, subtle touches you’ve found in SF or fantasy that are not widely known?