I started reading Fleming. Downloaded all the Bond epubs without guilt, since the author, son and wife are long dead and no one deserves the money.
So far, so good with Casino Royale. There's a definitely serious and better tone that was lacking in the campy movies from 60's and 70's.
I'm also reading The Riddle of the Sands, which arguably is thought to be the precursor to all XX's spy thrillers.