Travelweb.com has the following on weekend specials for this coming weekend:
Causeway Bay, 690HKD (Regal Hongkong Hotel)
Hong Kong, 700HKD (Regal Airport Hotel)
Kowloon, 650HKD (Regal Kowloon Hotel)
Kowloon, 400HKD (Regal Kaitak Hotel)
Kowloon, 700HKD (Grand Stanford Inter-Continental Hong Kong)
Shatin, 600HKD (Regal Riverside Hotel)
http://travelweb.com/TravelWeb/clk_locations.html
I have never monitored HKG but there are good specials for many places (Le Meridien in Nuernberg for DEM 120, Hilton Berlin for DEM 175).
FWIW, the booking engine (I think it's the same one as the planetholiday.com that ken hAAmer referred to) is used by some hotel chains.