My buddy Scott sent me this link: Sci-Fi Lists - Top 100 Sci-Fi Books. It is a pretty good list of the best books of the genre, although I'm sure people could argue about the order (and what's included or not included). As much I liked Dune, I'm not sure I'd consider it #1. 1984, for example, is a much more important book, although it tends to get all the attention for dystopian literature. For an alternative to 1984, check out We.

My recommendations from this list, in no particular order, would be:

• Ender's Game (my #1 probably)
• Any of the Neal Stephenson books, especially Diamond Age. I know Snow Crash is cooler (and I'll never forget the scene with the rail gun), I just felt like Diamond Age was neater.
• Lord of Light - which I've never read, but heard is very good. I was a huge fan of Zelazny's Amber series, which I hear is crap compared to Lord of Light.
• A Canticle for Leibowitz
• The Handmaid's Tale -feminism and sci-fi, interesting mix
• Flatland
• Neuromancer - I still like to think of security in terms of "ice"
• While not "high art", many of the Star Wars novels are pretty good, especially the Thrawn trilogy.

And while not a book - A Mind Forever Voyaging is the single best sci-fi game ever made.