Noah Smith has a list; all good stuff, although not all to my taste. (I just can’t read Cory Doctorow, and don’t know why). Definitely definitely The Dispossessed, which never seems to lose its relevance.

As I see some commenters have already pointed out, the list really must include Asimov’s Foundation Trilogy; ideally the new folio edition, for which guess who wrote the introduction.

I absolutely second (and third, and fourth) Charlie Stross. But Accelerando, although great, isn’t my top pick. He’s incredibly prolific, with the ability to write in multiple sub-genres, but if economics is what you want, you might want to look at the Merchant Princes novels, which are arguably parallel-universe fantasies that are also essays in development economics. (New edition of the MP novels coming out, with some plot snafus fixed). If you want sheer giddy fun, try the Laundry novels, Lovecraft-meets-hackers-meets-pop-references, with tips of the hat to everything from James Bond to Modesty Blaise.

Neal Stephenson: Actually, The Diamond Age is closest to being an econonovel. And I just loved Anathem.

And any Iain Banks Culture novel; Use of Weapons was my gateway, but Consider Phlebas, or actually any of them, will do. Banks is terminally ill, so his work should be especially treasured now.

Ken MacLeod: The Restoration Game is my favorite, but again there are many fine reads.

Read everything I’ve just mentioned, and you will wasted a large piece of your life. Hey, economists like to suppress their competition too!