io9 has its listing of these 20 best sci-fi books (some of which are really fantasy). I’ve read some, but mostly not. The following are those available for the Kindle. I haven’t checked other ebook formats:
Acacia – Durham
Confessions of Max Tivoli – Greer
Glasshouse – Stross
Perdido Street Station – Mieville
Jonathan Strange and Mr. Norell – Clarke
Look to Windward – Banks
The Mount – Emshweiller
Oryx & Crake – Atwood
World War Z – Brooks
Pattern Recognition – Gibson
Baroque Cycle – Stephenson
Of the ones I have read, I have to say that Perdido Street Station was one of the most impressive books I have ever encountered.