new code for this week is CINCO, gives 17% discount
I was searching for hotel in Paris and when I logged in the site gave me a 10% member discount (from what I was seeing earlier), plus the 17% from CINCO, for a total of 27%. Got a great hotel room for two next to Notre Dame for $113/night with breakfast and a view in the summer in a great 3-star, refundable, and it wasn't even the cheapest room in the hotel, just wow.
I think this means you should be searching logged in at the site, it could make a difference for some hotels.