These are John Carr's science fiction recommendations. All of these books can be found in the MIT Science Fiction Society library, though not all of them can be checked out.

I could argue literary merit vs. fun vs. scientific accuracy vs. broad appeal, but when I ask myself "which books would I most recommend" these come out at the top.

The books marked with "*" are especially recommended.

AuthorBookComments
Douglas Adams Hitchhiker's Guide to the Galaxy Silly SF. Read the first three in the series then stop.
Poul Anderson The Boat of a Million Years Immortals journey through history and beyond.
The High Crusade Aliens vs. primitive medieval earthlings. Great fun.
Neal Asher The Skinner "Welcome to Spatterjay ... where sudden death is the normal way of life."
Isaac Asimov The Foundation Trilogy After the fall of the Galactic Empire, is history being driven by the hand of a dead man? An SF classic. Avoid the modern sequels.
Iain M. Banks Use of Weapons* A great space adventure novel with a psychological component. Read this book. Pay attention.
Alfred Bester The Demolished Man In a world with telepaths, how can you get away with murder?
Robert S. Blum The Girl from the Emeraline Island The author's little-known first and last novel
Ray Bradbury R is for Rocket or S is for Space Story collections
David Brin Startide Rising and The Uplift War A contrast of large scale silly space opera with individual struggle for survival. In a single volume as Earthclan.
Frederic Brown From These Ashes A collection of old-fashioned, humorous science fiction
John Brunner Stand on Zanzibar The overpopulated world of 2010 seen from the 1960s
Arthur C. Clarke Childhood's End Inspiration for the Genesis song "Watcher of the Skies"
Rendezvous With Rama A classic "big dumb object" story.
Hal Clement Mission of Gravity The classic hard science fiction novel.
Greg Egan Axiomatic A collection of the short stories by "the best idea man in science fiction".
M. J. Engh Wheel of the Winds A pleasant novel of exploration.
Jasper Fforde The Eyre Affair Much more entertaining than any synopsis could make you believe.
Dave Freer and Eric Flint Rats, Bats, and Vats Mildly humorous military SF. Dumb humans vs. smart aliens.
Alexander Jablokov Nimbus Artificially enhanced people in decaying future America
James Alan Gardner Expendable In the future, misfits and unattractive people get assigned to dangerous missions.
Donald Kingsbury Courtship Rite A harsh world evolves a harsh culture.
Keith Laumer any Retief collection Read any of the Retief short stories (not novels) written before 1972.
George R. R. Martin Tuf Voyaging A man finds an abandoned ecological engineering starship and gets the chance to play god. Includes cats.
Jack McDevitt A Talent for War Despite the title it's not military SF.
The Engines of God Robert Frost was right.
Larry Niven Tales of Known Space A collection of short stories by the man who rejuvenated hard SF in the 1960s.
Ringworld The classic "big dumb object" story. Read after Tales of Known Space.
Larry Niven and Jerry Pournelle The Mote in God's Eye* A first contact story, and more. One of the great science fiction novels.
Alan Nourse The Universe Between Dated and arguably a juvenile, but a lot of people have good memories of this novel.
Frederik Pohl Gateway Brave adventurers with nothing left to lose fly in alien spaceships that they don't know how to steer.
Adam Roberts Salt Anarcho-communists and religious capitalists settle on the same world. What could go wrong?
Melissa Scott Dreamships Includes one of the most disturbing lines ever spoken by a fictional computer.
Charles Sheffield The McAndrew Chronicles A collection of hard science fiction short stories.
Robert Silverberg The Man in the Maze A member of the "alien death traps" micro-genre
Dan Simmons Hyperion Travelers on a quest share their powerful stories.
William Browning Spencer Résumé With Monsters Cthulhu gets involved in office politics.
Neal Stephenson Snow Crash A manic opening leads to a manic description of a balkanized, high tech future. Includes portable nuclear weapons and futuristic pizza delivery.
Arkady and Boris Strugatsky Roadside Picnic and Tale of the Troika The English translations are in a single volume.
William Tenn Immodest Proposals A collection of largely humorous science fiction
Timothy Zahn Time Bomb A collection of stories from when Zahn was good, in the 1980s.
Sarah Zettel Kingdom of Cages Researchers fight to understand the cause of ecological collapse before refugees force the issue.

Themes:

Alien Death Traps
The Man in the Maze, Roadside Picnic
Big Dumb Objects
Rendezvous with Rama, Ringworld, Mission of Gravity
Ecological engineering
Tuf Voyaging, Kingdom of Cages
Hard SF Authors
Hal Clement, Arthur C. Clarke, Greg Egan, Larry Niven, Charles Sheffield
Insane British Authors
Iain Banks
Weird
Tale of the Troika, Résumé with Monsters