By way of gwynraven

From The Guardian - the top 20 geek novels, the ones I've read in bold:

1. The HitchHiker's Guide to the Galaxy -- Douglas Adams
2. Nineteen Eighty-Four -- George Orwell
3. Brave New World -- Aldous Huxley
4. Do Androids Dream of Electric Sheep? -- Philip Dick
5. Neuromancer -- William Gibson
6. Dune -- Frank Herbert
7. I, Robot -- Isaac Asimov
8. Foundation -- Isaac Asimov
9. The Colour of Magic -- Terry Pratchett
10. Microserfs -- Douglas Coupland
11. Snow Crash -- Neal Stephenson
12. Watchmen -- Alan Moore & Dave Gibbons
13. Cryptonomicon -- Neal Stephenson
14. Consider Phlebas -- Iain M Banks
15. Stranger in a Strange Land -- Robert Heinlein
16. The Man in the High Castle -- Philip K Dick
17. American Gods -- Neil Gaiman
18. The Diamond Age -- Neal Stephenson
19. The Illuminatus! Trilogy -- Robert Shea & Robert Anton Wilson
20. Trouble with Lichen - John Wyndham