The Hitchhiker’s Guide to the Galaxy by Douglas Adams
Optimistic Space Scifi
101 books — 110 voters

Old Man's War by John Scalzi
The Old Man's War Universe
18 books — 15 voters
Bomb by Steve Sheinkin
Manhattan Project
56 books — 24 voters

Godless by Dan   Barker
Notable Atheist Books
590 books — 1,003 voters
The Demon-Haunted World by Carl Sagan
A Skeptic's Library
170 books — 126 voters

Rendezvous with Rama by Arthur C. Clarke
SF Masterworks
200 books — 728 voters
The Time Traveler's Wife by Audrey Niffenegger
Best Time Travel Fiction
2,172 books — 5,455 voters

I, Robot by Isaac Asimov
Best Science Fiction
3,850 books — 7,776 voters
Ender’s Game by Orson Scott Card
Military Science Fiction
855 books — 1,153 voters

Cosmos by Carl Sagan
Best Science Books - Non-Fiction Only
1,929 books — 3,628 voters
1984 by George Orwell
Best Dystopian and Post-Apocalyptic Fiction
4,011 books — 26,696 voters