CME Housing Futures
Starting in May 2006, the Chicago Mercantile Exchange started offering Housing Futures. There was a MarketWatch article in late May about it. The futures contracts are based on the S&P/Case-Shiller Home Price Indices, and the indices are currently calculated for 10 cities: Boston, Chicago, Denver, Las Vegas, Los Angeles, Miami, New York, San Diego, San Francisco, and Washington DC.
Even though I'm not planning on trading futures any time soon, following these particular futures could give an interesting read on where the housing market is going, since these indices are calculated based on recorded home sales prices and use a repeat sales methodology to try to isolate market changes (vs. change in value due to intrinsic property changes). Perhaps it will serve as a leading indicator for price performance of $HGX component stocks?