Of course, no list of this nature can ever be more than an abstract representation, given the astounding number of ideas that were inspired, anticipated, or outright invented by science fiction writers and the fact that SF writers tend to be part of the scientific, or at least engineering, community. Keep in mind that hard science fiction writers make their living by looking at the current state of science and technology and extrapolating from it. The best of them not only extrapolate the engineering, but take serious looks at its impact on society. The results are sometimes surprising, and often seem like sheer fantasy, which is why so many people use the term 'Science Fiction' to deride supposedly far-fetched ideas like global warming, identity theft, organ theft and extinction-level comet impacts. People who do this are never readers of hard SF - at most they may have endured a couple of Star Trek episodes or cracked open a Michael Crichton thriller during a long flight. These are often the same people who can be heard to proclaim "No one could have foreseen this", to describe catastrophic situations that finally come to pass twenty to thirty years after being described in science fiction books.

The writers, however, usually have a very good knowledge of technology and science - so good that they are often the only people qualified to comment on new developments (William Gibson is probably getting good and tired of responding to interviewers' questions on how he feels about the development of the World Wide Web). These writers are, quite often, engineers and scientists in their own right and have made significant contributions to their fields outside the pages of their stories - Arthur C. Clarke, for example, did invent the concept of satellites using a geosynchronous orbit, and found the exact orbit now used by most of our communications, weather and spy satellites.

Science fiction has, in the course of its history, been so entwined with actual science and technological development that it is often hard to say if a concept was invented by a scientist or an SF writer. The entire field of rocketry and space exploration has been propelled by SF just as much, if not more, than it contributed to the genre. Reusable spacecraft, satellites, lasers and gravity swingbys were all staples of SF long before they became reality. This does not necessarily mean they were first conceived in SF stories. The same can be said of almost all developments in the computer sciences - SF has been using computers practically since it was born. It has investigated every conceivable aspect of the field and made many predictions about computers. Some of these predictions came true. The vast majority of them did not.

However, it is fair to say that SF has at least driven the field of computer development with its rosy visions of future computers. By discussing the possibilities of computers that were faster, smaller and smarter than present technology allowed, SF may have given the engineers these goals. I'm sure a few engineers were convinced that ENIAC was as far as computers could go, but others were likely inspired by SF tales to continue pushing the envelope. This is, of course, pure speculation on my part. Total science fiction.

A few additions to ssd's list:

Magnetic Levitation ("maglev" for short, used on monorails and some rapid trains) - invented by Jonathan Swift in "Gulliver's Travels".

Organ Transplants - Mary Shelley, "Frankenstein".

Organ Theft - Larry Niven, sometime in the Sixties.

Teleportation - currently being researched as an offshoot of quantum mechanics, this is such an old idea in SF that I have no idea who came up with it first. Star Trek, of course, makes wide use of its "transporters", but the best account of teleportation's real-world effects has to be in Larry Niven's Known Space stories.

Digital Newspapers - another old idea, but the first use that I can remember offhand was in "2001: A Space Odyssey" (Arthur C. Clarke again)

Geosynchronous Orbit - Sir Arthur may not have invented the satellite (I'm not sure who did), but he certainly used them in his stories long before they existed and did, in fact, invent the geosynchronous orbit, AKA "The Clarke Orbit".

Walkmen - Ray Bradbury in "Fahrenheit 451", although I believe Clarke has also laid claim to this concept. I think Bradbury got there first.

Interactive Television - Ray Bradbury, "Fahrenheit 451". There is a good reason we call him "Uncle Ray". The man was not the best at inventing new technologies, but was astoundingly good at seeing the effects new technologies would have on people. He not only invented the concept of interactive TV, but immediately realised that it would be put to the most mind-numbingly mundane of uses - namely, personalizing the soap operas.

Robots - Karel Capek, "R.U.R." - 1920

Corrective eye surgery ("Lasik") - Isaac Asimov, "The Caves of Steel". Possibly even older.

Clones - another really, really old SF idea.

Remote Operation (AKA "Waldoing" or telefactoring) invented by Robert A. Heinlein in a 1942 story called "Waldo".

Global Warming - a list of the SF writers and the stories which have used this concept, recently accepted by an overwhelming majority of scientists and even more recently conceded by (some) politicians, would be far beyond the scope of this node and would probably be more suited to a doctoral dissertation or a book.