We actually booked our honeymoon before our wedding... by accident.
When we were at Disney in September, we booked the bounceback offer for free dining. I booked at the Polynesian (we always book at moderates), and I said, This better be our honeymoon for the amount of money we're paying for it. He said, Okay.
He proposed three months later, and we figured, might as well make the wedding right before our trip.