Does anybody have any little-known SF authors that they would recommend to other readers?

I nominate Cory Doctorow, Olivia Butler, Ted Chiang, Gwyneth Jones, and Tobias Buckell.

Any other authors the rest of us should take a look at?

Definitely Octavia E. Butler!

Also Sean Stewart. He's a little-known Canadian SF/Fantasy author; I love his fantasy novel Nobody's Son, but his SF novels Resurrection Man and Mockingbird are also superb.

Sherri S. Tepper. My favorites are The Family Tree and her True Game series (which starts out feeling like fantasy but is obviously SF by the third book).

Connie Willis. Hugo and Nebula award-winning author for both her short fiction (some of which you can read here: www.freesfonline.de/authors/Connie_Willis.html) and she can be both emotionally ravaging (like in Doomsday Book) and incredibly, incredibly funny (like in To Say Nothing of the Dog and Bellwether).

Gordon R. Dickson. One of the lesser-read of the Golden Age authors, I think his Childe Cycle is wonderful (especially Soldier, Ask Not) and Time Storm is still one of my favorite novels.

And finally, for short fiction, no one can beat James Tiptree, Jr. Her stories are searing, brilliant pieces of work that justly took the field by storm in the 70s, and though there wasn't a huge backlash when she was revealed to be a woman, she never did quite recover her place. Her life ended tragically, but what she did while she was here was phenomenal.

Looking back at my past five years of reading, the best "obscure" author I've read is Bob Shaw, who does some great satire.  Who Goes Here? was especially good.  Also, here are a few more I liked, but I've only read a single book by: 

Augustine Funnell (Brandyjack)

F.M. Busby (Cage a Man)

John Boyd (The Last Starship From Earth)

E.C. Tubb (Century of the Manikin)

Matt, that's impressive! I've never heard of any of them! Are they American, British, or some other nationality? And what era did they write during?

I've gotten a lot of oddball books in eBay lots, and I collect DAW books, and some of the older authors they publish aren't very well known.

Bob Shaw is British, and wrote a number of books in the '60's through the '80s, and some in the '90s, bt he died in 1996.

I can't find any info on Augustine Funnell.  His one book, Brandyjack, was published by Laser Books in 1976.  This is an oddball series from 1975 and '76 I am trying to collect.  I know some of the authors used pen names, so maybe Funnell is too (ETA - Wikipedia shows his name come up twice as a contributor to short story collections).

F.M. Busby is American, and wrote from the '70s to '90s.  He died in 2005.

John Boyd is still alive as far as I can tell, but only wrote a few novels...the most recent one being from 1978.

E.C. Tubb is probably the most well known of that list.  He is a hugely prolific British author, born in 1919 and still alive.  He wrote the long Dumarest of Terra series, the 33rd book of which just came out last year.  He's used at least 10 different pseudonyms as well.

Considering the awards these authors have won, not really obscure, but I suggest. Jeff Noon, Peter Watts, Geoff Ryman (Air), Jeff VanderMeer, and Kathleen Goonan

I can strongly recommend:

Matthew Stover and his series beginning with Heroes Die

and Kirstein Rosemary's Steerswoman series

Rosemary and Stover combine the SF and fantasy genre in a way I didn't think possible. 

I think you meant Octavia Butler, not Olivia Butler. Some excellent SF, it was a great shame when she passed away.  I liked Bob Shaw too, especially his "slow glass" short stories. And Rosemary Kirstein's books are very good, although it's frustrating waiting for her to end that series. It's been years since the last one but I didn't get any sense of closure on it. 

How about Kage Baker's "Company" novels, I'm not sure if she qualifies as little-known, but they're not Generic Extruded Fantasy Product at least; I run into way too much of that. I just read "Old Man's War" by John Scalzi, I'd never heard of him before, and I liked it very much.  Best series I read last year was by Karen Traviss, starts with "City of Pearl".

I thought about Kage Baker, but since I've only read her short fiction I didn't know if I was qualified to recommend her. I've wishlisted the first Company novel and I'm looking forward to eventually getting it.

I wouldn't consider John Scalzi little known, simply because at least you can still find his books at Barnes and Noble and Borders; though with the way they're shrinking their sections, he probably won't be there for much longer. It makes me so sad to go into chain bookstores these days!

A while before any of us were born (1920) a Czech satirist named Karel Capek gave the world the word robot. R.U.R.  ( Rossum's Universal Robots) is a social satire. I don't think the term Science Fiction was around yet. In 1936 he wrote what I think as a truly unique book, The War With The Newts. It is also written as social satire, not Science Fiction. Sci-Fi or Fantasy? Somewhere in between, I would venture. I think it is really good, even if we do lose the war. It isn't impossible to get hold of the book, though not real easy either.

City of Pearl series is great !

Delia Marshall Turner.  I often recommend Of Swords and Spells as a YA SF novel.  Only 2 books.

Kelley Eskridge.  I really liked Solitaire.

I've always loved Sheri Tepper's  Marianne Trilogy.  Would that be fantasy?

I haven't read that trilogy, but I have noticed that Sheri S. Tepper often writes in that grey area between SF and fantasy. . . novels that feel like fantasy (low level of technology, magic) but which turn out to have SF explanations. It's kind of an old-fashioned way of writing, more common to authors from the 70s and 80s than the 21st century. I personally like that style, and I love Tepper's writing.

It's kind of an old-fashioned way of writing, more common to authors from the 70s and 80s than the 21st century.

Wait... when did 70s and 80s become old fashioned?  Sigh... now I feel old... Phoenix, you wound me... ;)

LOL! So sorry, Paul H! I should have chosen my words differently. Ummm. . . what if I had said "It's a way of writing that has fallen out of fashion"?

I do love that junction between the two genres. . . and thinking about it, while it isn't as common as it used to be it hasn't disappeared altogether. Sharon Shinn's Samaria series is sci-fi that feels like fantasy, and some of Iain Banks' Culture novels have sections on low-tech, medieval planets in between the space-faring sections.

Grandpa Paul!

(ETA - I became a serious Shakespeare guy in college...if you read that long enough, anything after 1700 sounds downright modern)

Gee thanks Matt... LOL  Maybe I should consider changing my screen name!

(Am totally with you on the Shakespeare, though.  I prefer the tragedies over the comedies or histories... King Lear is one of my absolute favorite stories ever!)

With The Revenger's Tragedy , The White Devil, and above both of these, The Duchess of Malfi, John Webster was almost, if not , the equal of Shakespeare at his best. Don't believe me, check them out. And throw in Chapman's Bussy D'Ambois.

No one can be Shakespeare's equal!  Sorry, but Shakespeare people are a close-minded lot when it comes to #1 :-p

Don't believe me. REad The Duchess of Malfi. You think Iago was bad. Bosola was the baddest of the bad. You want a great female protagonist. Shakespeare has none like The Duchess. I never said Webster was the equal of Shakespeare. I said that Webster's best was as good as Shakespeare's best , abeit there was not near as much of it and Bill The Bard was truly great probably a dozen times.

And I said, true Shakespeare fans will never, ever admit he had an equal...I said it tongue in cheek, but it's true...also, I am not necessarily including myself in that number.  I was into SF before Shakespeare.

Back to little-known authors...I think James Blish is fading into obscurity as well.  A couple of his books had a sort of cult following, but I think that's about finished.  He's a little "old-fasioned" as well :-p

My favorite "little known" SF author is Melissa Scott. She creates brilliantly written, fascinating worlds with detailed cultures and interesting characters. My favorite of her books is "Dreaming Metal" - I think I've given away at least a dozen copies of it to friends already. 

I also had the pleasure of hanging out with her for an hour or so at Worldcon a few years back, and she is a witty and charming person.

I don't know if you could consider Martin Caidin a little known Sci Fi writer (after all, he is the man responsible for creating the six million dollar man series from his book the Cyborg), but I do really enjoy reading his books.

Eric Frank Russell is another author from the 50's that I loved.    I think he was better know for his short stories than novels, but both were well done.  Good luck finding any of his works, however.