more detailed lists here

2003 The Speed of Dark by Elizabeth Moon (Ballantine)

2002 American Gods by Neil Gaiman (Morrow & Co.)

2001The Quantum Rose by Catherine Asaro

2000 Darwin's Radio by Greg Bear

1999 Parable of the Talents Octavia Butler

1998 Forever Peace by Joe Haldeman

1997 The Moon and the Sun by Vonda N. McIntyre

1996 Slow River by Nicola Griffith

1995 The Terminal Experiment by Robert J. Sawyer

1994 Moving Mars by Greg Bear

1993 Red Mars by Kim Stanley Robinson

1992 Doomsday Book by Connie Willis

1991 Stations of the Tide by Michael Swanwick

1990 Tehanu by Ursula K. LeGuin

1989 The Healer's War by Elizabeth Scarborough

1988 Falling Free by Lois McMaster Bujold

1987 The Falling Woman by Pat Murphy

1986 Speaker for the Dead by Orson Scott Card

1985 Ender's Game by Orson Scott Card

1984 Neuromancer by William Gibson

1983 Startide Rising by David Brin

1982 No Enemy but Time by Michael Bishop

1981 Claw of the Conciliator by Gene Wolf

1980 Timescape by Gregory Benford

1979 Fountains of Paradise by Arthur Clarke

1978 Dreamsnake by Vonda N. McIntyre

1977 Gateway by Frederick Pohl

1976 Man Plus by Frederick Pohl

1975 Forever War by Joe Haldeman

1974 The Dispossessed by Ursula K. LeGuin

1973 Rendezvous with Rama by Arthur C. Clarke

1972 The Gods Themselves by Isaac Asimov

1971 A Time of Changes by Robert Silverberg

1970 Ringworld by Larry Niven

1969 The Left Hand of Darkness by Ursula K. LeGuin

1968 Rite of Passage by Alexei Panshin

1967 The Einstein Intersection by Samuel R. Delaney

1966 Flowers for Algernon by Daniel Keyes

1965 Dune by Frank Herbert