I've never found a history of world-building as an artform. I'm not talking about political utopias, but simply building imaginary worlds that are at least plausible on physical, biological, evolutionary and social/political levels. Though creating imaginary worlds is an urge that's always been with us, it's exploded in the last century, largely because for the first time we understand in at least a general way what makes a biosphere work (even if politicians ignore that hard-won knowledge). Still, what follows is just a list of personal influences; really, my omission of most mythic and utopian worlds is quite arbitrary.

LITERATURE

I learned the art of world-building from science fiction writers. In a field this complex, amateurs can often outguess specialists, for planet-building is like juggling: you must toss many factors around in an even-handed sort of trance. The moment you over-focus on any single ball, it all falls down.

Some pioneers of the art:

OLAF STAPLEDON (1920s)

Star Maker: the history of mind in the universe as a whole, as it integrates on higher levels until as a world-spirit it meets its creator. The only novel I can think of whose protagonist is consciousness itself. And his Sirius is one of the best early portraits of an intelligent nonhuman. What I learned from Stapledon wasn't specific techniques but simply that you can make species and civilizations and ecosystems your characters; you can think big.

J.R.R. TOLKIEN (1920s-1960s)

Not a science fiction writer, but a master worldbuilder: Middle Earth, unlike earlier mythology and fantasy, has the complexity and (more important) consistency of a real world. The Lord of the Rings isn't linear, but fractal: self-similar, with endlessly echoing motifs and digressions. Mapped, the narrative looks more like a snowflake than a line; and those digressions in space and time define his world.
I was also influenced by his long essay "On Fairy-Stories", the nearest thing to a guide for the literary end of the world-building craft. He argues that creativity is literally playing God, is exactly analogous to divine creation--the same thing on a smaller scale (and is sacred, not sacrilegious). The creation of another world is fundamentally different from mainstream fiction's selective evocation of the given world, and requires a different pace and focus.

POUL ANDERSON (1940s to 1990s)

A hard-science craftsman who grasped the way a world's orbit, chemistry, size, tilt and so on could shape not just its climate and biology but its people's biology and psychology. He literally wrote the book on it: the first formal guide to world-building, though I've never found a copy. Instead I learned from his fiction, like The Man who Counts and People of the Wind, plus short stories like "The Longest Voyage." My world Lyr is a tribute to him.

URSULA LEGUIN (1960s- )

The Dispossessed is one of very few novels to describe a workable alternative to capitalist democracy. It was a tribute to anarchist Emma Goldman--giving her her own world! The anarchist planet in The Dispossessed directly inspired my own Serrana, a biosphere with half a dozen intelligent species, exploring Kropotkin's ecologically based anarchism, just as Le Guin embodied Goldman's ideas on social cooperation.
Her essays in Language of the Night map the gulf between realism and fantasy, and has solid advice for any world-builder, particularly on names, style, and scope vs. intimacy.

LARRY NIVEN (1960s-1990s).

Niven's an anti-influence. He's a well-known world-builder (even gives workshops on it) but his characters and cultures leave me cold... as do his right-wing politics. His best-known creation, Ringworld, feels like a big empty downtown with no street life--he's an engineer, but no architect, and the book reveals the difference. I've steadily moved away from Niven-like macroengineering to more intimate pictures of daily life on alternate worlds.

KIM STANLEY ROBINSON (1990s- )

Red Mars, Green Mars, and Blue Mars. An eco-anarchist saga, strongly idealistic (after a savage first chapter that scared off half my friends). Impressive travel-writing, too... No? You try to describe a place you've never been, based only on satellite photos! My Mars Reborn is a tribute/critique of Robinson's terraforming job, and an attempt to supply the one thing the books lack: a good map.

NONFICTION

PETER WARD DOUGLAS (1980s- )

Rare Earth argues that intelligent life (indeed, anything more complex than bacteria) require a rare combination of factors, all of which must be quite Earthlike. Douglas ignores how many of his factors can affect each other--differences can even cancel each other out. In Future Evolution, he assumes that once we're gone, no other intelligent species will evolve. Why? My doubts led to the series The Biosphere Variations , showing ways that worlds unlike Earth might support intelligent life.

JARED DIAMOND (1990s- )

His Pulitzer-winning Guns, Germs and Steel explores the environmental factors leading to social and technological progress (or lack of it). In some cases sheer geography alone explains progress (for example, a narrow east-west strip will progress faster than a north-south one: crops can spread faster. And a crossroads may suffer more wars, but also collects innovations.) My world Jaredia is a tribute, as well as a thought-experiment using his theories in a world they weren't designed for...

JONATHAN ADAMS (1990s- )

A paleoclimatologist, he's mapped pollens found in Ice Age strata and deduced regional climates from them. His maps suggest that as the world grew colder, forests shrank and lands dried. The corollary: global warming may cause a wetter climate than we project. See his maps at http://members.cox.net/quaternary/
Shiveria is a tribute to his work.

VISUAL ART

REMOLIA? (1970s)

Years ago I saw an art-magazine article on two Italian metalworkers who built a sketchy, hollow alien planet several meters wide, with girders for meridians, seas of empty air, and continents of steel. Was it called Remolia? No, that was one continent, I think. I've never traced it on the Web and I don't know their names; but I never quite forgot their world. Not its details, or style, or plausibility--but just that they did it--and on such a scale.

HENRY DARGER (1960-70s)

A few years back, a San Francisco museum exhibited pieces of the massive fantasy world Henry Darger created in his Chicago apartment. I was moved and impressed by his epic fantasy about children rebelling against adult abusers with the help of strange angels--part human, part mountain sheep, part dragon. I recognized a kindred spirit. The exhibit bristled with notes arguing the old man's obsessions didn't prove he was a psychotic child molester... the exhibitors' utter incomprehension of what he was doing taught me I was a Darger too... and might as well get used to it.

A WALK THROUGH TIME (1990s)

But those are all indirect influences. What directly inspired these globes were some really bad ones! In the nineties, the California Academy of Sciences in San Francisco built a long-term exhibit: a walk through time. Each geological era had a room of its own, with fossils and some pretty nice dioramas and a globe showing Earth as it had been in that era. Only not! These globes had puffy continents (too vertically exaggerated) with vague mountain ranges--they looked like bread dough or scabs, except they were colored battleship-gray. There were no icecaps, river systems, or vegetation to indicate climate--either regional or global. The only thing marked was the border of the United States! Ah, yes, it existed before the dinos, and will endure to the end of time...
Not only were all the continents like wet cement, making you feel like Earth never really firmed up into a real place until wonderful we came along... they didn't even give a sense of their geologic era--was the world hot, cold, wet, dry, covered in ice? Couldn't tell by these suckers. Still, they were art, not mere maps--for they did express emotion. Institutional emotion. They expressed fear. The fear of making a mistake, or offending someone's pet theory, or suggesting knowledge where there's only guesswork. The fear of looking unscientific!
The result was more misleading than any opinionated speculation could ever be.
That was a deep lesson. I went home all hot to build a better planet, a vivid, specific, opinionated planet...
...and couldn't stop. I tell you, they're like potato chips.