I found this list of the 100 Science Fiction Books You Just Have to Read. I've added remarks to which ones I've read.

1 Childhood's End, Arthur C. Clarke
2 Foundation, Isaac Asimov (Read it)
3 Dune, Frank Herbert (Started to read it)
4 The Man in the High Castle, Philip K. Dick
5 Starship Troopers, Robert A. Heinlein (Read it)
6 Valis, Philip K. Dick
7 Frankenstein, Mary Wollstonecraft Shelley (Read it - Didn't like it)
8 Gateway, Frederik Pohl
9 Space Merchants, Frederik Pohl
10 Earth Abides, George R. Stewart
11 Cuckoo's Egg, C.J. Cherryh
12 Star Surgeon, James White
13 The Three Stigmata of Palmer Eldritch, Philip K. Dick
14 Radix, A. A. Attanasio
15 2001: A Space Odyssey, Arthur C. Clarke (Read it, Saw the movie)
16 Ringworld, Larry Niven
17 A Case of Conscience, James Blish
18 Last and First Man, Olaf Stapledon
19 The Day of the Triffids, John Wyndham (Saw the movie)
20 Way Station, Clifford D. Simak
21 More Than Human, Theodore Sturgeon
22 Gray Lensman, E.E. "Doc" Smith
23 The Gods Themselves, Isaac Asimov
24 The Left Hand of Darkness, Ursula K. Le Guin
25 Behold the Man, Michael Moorcock
26 Star Maker, Olaf Stapledon
27 The War of the Worlds, H. G. Wells (Read it)
28 20,000 Leagues Under the Sea, Jules Verne (Read it)
29 Heritage of Hastur, Marion Zimmer Bradley
30 The Time Machine, H. G. Wells (Read it)
31 The Stars My Destination, Alfred Bester (Read it ** Great book)
32 Slan, A. E. Van Vogt
33 Neuromancer, William Gibson (On this years reading list)
34 Ender's Game, Orson Scott Card
35 In Conquest Born, C. S. Friedman
36 Lord of Light, Roger Zelazny
37 Eon, Greg Bear
38 Dragonflight, Anne McCaffrey
39 Journey to the Center of the Earth, Jules Verne (Read it)
40 Stranger in a Strange Land, Robert A. Heinlein (Read it - great book)
41 Cosm, Gregory Benford
42 The Voyage of the Space Beagle, A. E. Van Vogt
43 Blood Music, Greg Bear
44 Beggars in Spain, Nancy Kress
45 Omnivore, Piers Anthony
46 I, Robot, Isaac Asimov (Started to read it, movie not related)
47 Mission of Gravity, Hal Clement
48 To Your Scattered Bodies Go, Philip Jose Farmer
49 Brave New World, Aldous Huxley
50 The Man Who Folded Himself, David Gerrold
51 1984, George Orwell (Read it)
52 The Strange Case of Dr. Jeckyl And Mr. Hyde, Robert Louis Stevenson (Read it)
53 Snow Crash, Neal Stephenson (On this years readling list)
54 Flesh, Philip Jose Farmer
55 Cities in Flight, James Blish
56 Shadow of the Torturer, Gene Wolfe
57 Startide Rising, David Brin (Have book, but not read yet)
58 Triton, Samuel R. Delany
59 Stand on Zanzibar, John Brunner
60 A Clockwork Orange, Anthony Burgess (Saw the movie)
61 Fahrenheit 451, Ray Bradbury (Read it)
62 A Canticle for Leibowitz, Walter M. Miller Jr.
63 Flowers for Algernon, Daniel Keyes
64 No Blade of Grass, John Christopher
65 The Postman, David Brin (Saw the movie)
66 Dhalgren, Samuel R. Delany
67 Berserker, Fred Saberhagen
68 Flatland, Edwin Abbott Abbott
69 Planiverse, A. K. Dewdney
70 Dragon's Egg, Robert L. Forward
71 Downbelow Station, C. J. Cherryh
72 Dawn, Octavia E. Butler
73 The Puppet Masters, Robert A. Heinlein (Read it)
74 The Doomsday Book, Connie Willis (Started to read it)
75 Forever War, Joe Haldeman
76 Deathbird Stories, Harlan Ellison
77 Roadside Picnic, Arkady Strugatsky
78 The Snow Queen, Joan D. Vinge
79 The Martian Chronicles, Ray Bradbury (Read it)
80 Drowned World, J.G. Ballard
81 Cat's Cradle, Kurt Vonnegut
82 Red Mars, Kim Stanley Robinson
83 Upanishads, Various
84 Alice in Wonderland, Lewis Carroll (Read it)
85 The Hitchhiker's Guide to the Galaxy, Douglas Adams (Read it several times)
86 The Lathe of Heaven, Ursula K. Le Guin
87 The Midwich Cuckoos, John Wyndham
88 Mutant, Henry Kuttner
89 Solaris, Stanislaw Lem
90 Ralph 124C41+, Hugo Gernsback
91 I Am Legend, Richard Matheson
92 Timescape, Gregory Benford
93 The Demolished Man, Alfred Bester
94 War with the Newts, Karl Kapek
95 Mars, Ben Bova
96 Brain Wave, Poul Anderson
97 Hyperion, Dan Simmons
98 The Andromeda Strain, Michael Crichton (Read it, saw movie)
99 Camp Concentration, Thomas M. Disch
100 A Princess of Mars, Edgar Rice Burroughs

You can find information on each of these books at the article I found. Some of these I've heard of, others I've not.