Harbour Town Shopping Centre. It's a bit out of the way from the 'touristy' shopping areas of Broadbeach/Surfers/Southport, but definately worth a visit. The whole place (and let me tell you - IT'S HUGE!) is full of bargain shopping. Here you'll find factory outlets for every type of fashion possible - even the big european designer labels - over 50% off normal retail prices. This is the website listing all of the shops, etc.
You can spend ALL day here!
Pacific Fair Shopping Mall. It is not unlike other shopping malls, except it is very very big. It is more like a shopping suburb. Apparently it is the biggest in the Southern Hemisphere. Things aren't particularly different from everywhere else in Queensland or Brisbane, but it has an excellent atmosphere (or ambience). Just walking around is very comfortable.