MASTERCARD
Seems pretty good from the test search I did for January 2014. It applied a 25% discount as the rate varied across the random time period I selected.
Code doesn't work for any more or less nights in the same booking.
Exclusions:
Venetian Macau Resort
Sands Macao Hotel
Marina Bay Sands Singapore
Harrah's
MGM
Starwood
Novotel
Sol Melia
Rezidor
Hilton
InterContinental
Accor
Sofitel
Mercure
Ibis
Pullman
MGallery
Suite hotel
All Seasons
Orbis
Marriott.
From site:
"1. Visit Webjet Hotels and search for a four night stay in the destination of your choice.
Select the hotel and then room you'd like to book.
Proceed to the payment page and apply code MASTERCARD.
Then complete payment with your MasterCard to get your four night booking for the price of three."
Booked my honeymoon in Fiji for April next year. Lots to choose from. We saved $560 - thanks wherestheid!