There's no shortage of sites to help you find hotel rooms or serviced apartments, but if you want to safely rent a private house or apartment for a short-term stay, the options are more limited. Roomorama offers global listings of properties available for rent, giving you the option of a more individual and potentially cheaper experience.
The biggest potential risk with renting a property through a private owner is uncertainty over how accurate the descriptions are and concerns over how you'll pay. Roomorama vets its hosts before allowing properties to be listed, and handles payments itself; owners don't receive the payment until after they've been given a code by the renter after they have successfully "checked in". Properties can be rented from 1 to 90 days, and cover the gamut from individual rooms in houses to luxury multi-bedroom villas.
Roomorama is currently finalising an iPhone app which will include additional perks such as cached directions from the airport to your accommodation. It's free to search, with a booking fee attached to any properties you do decide to book.