[PatrickHenry]

Among early SF writers (ignoring some really ancient stuff -- like the Odyssey) are Washington Irving (the guy who woke up 20 years later, a kind of time travel story); Mark Twain (Conn. Yankee, definitely time travel); and Charles Dickens (Christmas Carol, also time travel, but without the "machine" which HG Wells supplied later). I think Hans Christian Anderson did one about seven-league boots and some kind of consciousness swapping, but that may have been Dickens. Oddly, I can't think of any SF written by Poe. Anyone?

[Doctor Stochastic]

"The Narrative of Arthur Gordon Pym of Nantucket" comes close.

(He wasn't the "Man from Nantucket" though.)

[balrog666]

All this wonderful sci-fi and fantasy talk and nobody's mentioned Jack Vance, Roger Zelazny, Terry Pratchett, David Brin, or Vernor Vinge?

I loved A.E. van Vogt, Phillip Jose Farmer, Robert Heinlein, Keith Laumer, et al. as much as the next guy, but ... some of them hold up better than others.