The Economist magazine has relaunched a triple Iberia Plus miles offer for subscribing to the Magazine and digital editions by June 30, 2015.
You would normally get 4,000 miles for one year subscription that is tripled to 12,000 miles during this promotion.
You can access this offer on The Economist website here.
Note that the price of the subscription greatly varies between countries and the bonus miles offered is not 12,000 miles universally.
The price for North America is significantly lower compared to other regions but seems that their bonus miles are now capped at 8,000.
I have subscribed for The Economist in the past and always try to have one with me for the long-haul flights. You can spend several hours reading through the magazine.