Asking the hive mind (or the human database, as I like to call it) to identify the title and author of a story one remembers from long ago is something that goes back to the early days of the Usenet and SF-Lovers Digest. I remember that certain plots were asked about so many times that they ended up in the FAQ. (Some of those included "The Last Question" by Isaac Asimov, "Light of Other Days" by Bob Shaw, "A Sound of Thunder" by Ray Bradbury, and "The Star" by Arthur C. Clarke.)
Anyway, every time I see one of these requests, a mischievous impulse tries to convince me to turn this inquiry game into a hoax. That is, it prompts me to go on one of these bulletin boards and to describe a story that as far as I know doesn't actually exist...and then to see what real stories people think I'm remembering.
Who knows? Maybe one can build up a list of cool stories to track down that way.