WisdomTree International Real Estate Fund (DRW) has a respectable expense ratio of 0.58%. The weighting is primarily in the countries Australia, Hong Kong and Japan; a third of the ETF is in Europe. The firm claims a backtested return of over 14% over the past 10 years, trouncing the S&P500 return of around 8%. I would certainly recommend this ETF as a 5-10% portion of any portfolio given its international diversification, its sector diversification and its ability to withstand market downturns due to the high yield component of the individual holdings.
Granted, the international and emerging markets have been extremely hot and do carry significant volatility, but the U.S. market is somewhat saturated now as well. In addition to some commodities and some conservative components, this instrument would be a healthy addition to any portfolio absent other similar holdings.