The Hitchhiker’s Guide to the Galaxy by Douglas Adams
Optimistic Space Scifi
98 books — 104 voters

Old Man's War by John Scalzi
The Old Man's War Universe
18 books — 15 voters
Bomb by Steve Sheinkin
Manhattan Project
55 books — 23 voters

Godless by Dan   Barker
Notable Atheist Books
552 books — 950 voters
The Demon-Haunted World by Carl Sagan
A Skeptic's Library
170 books — 127 voters

Rendezvous with Rama by Arthur C. Clarke
SF Masterworks
203 books — 723 voters
The Time Traveler's Wife by Audrey Niffenegger
Best Time Travel Fiction
2,001 books — 5,284 voters

I, Robot by Isaac Asimov
Best Science Fiction
3,692 books — 7,070 voters
Ender’s Game by Orson Scott Card
Military Science Fiction
840 books — 1,135 voters

Cosmos by Carl Sagan
Best Science Books - Non-Fiction Only
1,839 books — 3,603 voters
1984 by George Orwell
Best Dystopian and Post-Apocalyptic Fiction
3,777 books — 26,038 voters