Edit: Code updated. Still the same deal.
Enter the coupon at the search page. Offers valid at participating hotels (showing "PROMO CODE ELIGIBLE"). Travel date until December 31, 2015. Maximum $500 discount per booking.
In case you never heard of them: They are from US, same company as Hotelclub, Orbitz, ebookers and RatesToGo. Prices are in USD so you need a 28 degree card to avoid international transaction fees. Discount do not apply on fees and charges, which you will see them before you enter any booking information.