There are so many different names for condos to rent and different sites too. Here are some good general ones:
Homeaway.com is a good general site that has private listings. Particularly strong in Australia, check out the cool tower in Melbourne and the listings in Hamiton Island as examples.
Holiday Homes Hamilton Island has the top Google ranking and a good listing, but therefore not great availability. The one that is a little hidden is HamiltonIsland.biz
