Bolded the ones I've read.
1. The Demolished Man by Alfred Bester (Tension, Apprehension, and Dissension have begun!) (Just watched the B5 episode in which we discover that Psicop Mr. Bester's first name is, of course, Alfred.
2. They'd Rather be Right/The Forever Machine by Mark Clifton and Frank Riley
3. Double Star by Robert A. Heinlein
4. The Big Time by Fritz Leiber
5. A Case of Conscience by James Blish
6. Starship Troopers by Robert A. Heinlein
7. A Canticle for Leibowitz by Walter M. Miller, Jr.
8. Stranger in a Strange Land by Robert A. Heinlein One of the works I consider less deserving. SiaSL shows the first signs of RAH's decline, IMCGO
9. The Man in the High Castle by Philip K. Dick
10. Way Station by Clifford Simak
11. The Wanderer by Fritz Leiber
12. . . . And Call Me Conrad/This Immortal by Roger Zelazny I think this was rather weak compared to other Zelazny; perhaps this was one of those awards where they're really giving it for the sum total of your work to date?
13. Dune by Frank Herbert
14. The Moon is a Harsh Mistress by Robert A. Heinlein
15. Lord of Light by Roger Zelanzy
16. Stand on Zanzibar by John Brunner
17. The Left Hand of Darkness by Ursula K. Le Guin
18. Ringworld by Larry Niven
19. To Your Scattered Bodies Go by Philip Jose Farmer
20. The Gods Themselves by Isaac Asimov
21. Rendezvous With Rama by Arthur C. Clarke
22. The Dispossessed by Ursula K. Le Guin Color me unimpressed.
23. The Forever War by Joe Haldeman
24. Where Late the Sweet Birds Sang by Kate Wilhelm
25. Gateway by Frederik Pohl
26. Dreamsnake by Vonda McIntyre
27. The Fountains of Paradise by Arthur C. Clarke
28. The Snow Queen by Joan D. Vinge
29. Downbelow Station by C. J. Cherryh
30. Foundation's Edge by Isaac Asimov
31. Startide Rising by David Brin
32. Neuromancer by William Gibson
33. Ender's Game by Orson Scott Card
34. Speaker for the Dead by Orson Scott Card
35. The Uplift War by David Brin
36. Cyteen by C. J. Cherryh
37. Hyperion by Dan Simmons Color me even more unimpressed.
38. The Vor Game by Lois McMaster Bujold
39. Barrayar by Lois McMaster Bujold
40. A Fire Upon the Deep by Vernor Vinge
41. Doomsday Book by Connie Willis
42. Green Mars by Kim Stanley Robinson
43. Mirror Dance by Lois McMaster Bujold
44. The Diamond Age by Neal Stephenson
45. Blue Mars by Kim Stanley Robinson
46. Forever Peace by Joe Haldeman
47. To Say Nothing of the Dog by Connie Willis
48. A Deepness in the Sky by Vernor Vinge Amazing book.
49. Harry Potter and the Goblet of Fire by J. K. Rowling
50. American Gods by Neil Gaiman
51. Hominids by Robert J. Sawyer
52. Paladin of Souls by Lois McMaster Bujold
53. Fahrenheit 451 by Ray Bradbury (Retro Hugo)
54. The Mule/Foundation and Empire by Isaac Asimov (Retro Hugo)
55. Farmer in the Sky by Robert A. Heinlein (Retro Hugo)