There's a documentary called "How William Shatner Changed the World" that talks about how Star Trek inspired a lot of big technical advances -- for example, the guy who invented the cell phone admits that he was inspired by the handheld communicator from the original Star Trek. Arthur C Clarke, aside from writing 2001, 2010, Rendezvous with Rama, and a lot of other really good sci-fi, also invented the geostationary satellite. He put forth the idea in an opinion piece called "Extra-Terrestrial Relays." Isaac Asimov wrote a great many books that essentially explained science in layman's terms. Jerry Pournelle used to work for the Department of Defense during the cold war. From what I understand a great many hard SF/military SF writers during that time did. He also created the Pournelle chart which he put forth as the most accurate way to measure political belief. Wikipedia states he created this in 1963 -- it looks a lot like the grids you see in a lot of web tests these days. Larry Niven's Ringworld is considered semi-seriously in some scientific circles, not necessarily as something that could be built, but as a very plausible explanation of what such a structure would be like if it somehow were. Of course it was influenced by the Dyson sphere... Robert Heinlein may have invented the mass driver in The Moon is a Harsh Mistress. I can't think of anything earlier than that, but I don't know for certain. Oh, also, Philip K. Dick gave some guy an idea for a movie about Harrison Ford hunting down robots.