I found Damien's post very interesting. I remember as a teenager coming across a copy of Olaf Stapleton's book and being enthralled by it with the quaint but fascinating approach it took to describing humanities future. I had thought it was a work that had been simply forgotten and now I learn of all this!
I have only read one novel of Lem. I forget the title but the main character was an astronaut who returns to Earth after having been gone for centuries. He is seen as a dangerous throwback in a world where everyone has been "treated" to be nonviolent. I remember how the cars had a crash avoidance system in them and he tore his out. A popular actress wanted to make love to him because he was such a "savage" even though she experienced barely controlled terror around him.
I knew of Lem's stature but never got around to reading any more of his books though I enjoyed the one I did read. I was fascinated to see that Lem had actually critiqued the book I had thought lost into obscurity when I found it in a used bookstore years ago.
One of my favorite stories in a somewhat similar vein is "Twilight" by John W. Campbell. I loved how the visitor from the future catches a ride from a rather regular guy in a truck and tells him of the histroy of humanity. Few stories as a young teen caught my imagination like this one did. I need to go back and reread it.