I was going to say Black Swan, which I would say has changed how I think about myself, knowledge and the mechanics of society and the world this year.

I've got Antifragile queued up next.

Fooled by Randomness is excellent also; they all have the same message but it's the most direct

I haven't read the Black Swan. I skimmed a few places and know a Taleb fan who has read both Fooled by Randomness and Black Swan. With moderate confidence I'd say FbR is the better book - Black Swan seems to be much of the same material presented for a wider audience. I thought FbR was excellently written, regardless of the content.