A post at Freakonomics (and accompanying article at Slate) advocates protection against price depreciation as a way to prop up housing prices:

Sellers could commit to reimbursing their buyers for any fall in the average value of homes in their area in the year following a sale. Such price protection would give buyers confidence that they won’t regret their purchases even if the market does fall further and cheaper houses come on offer — confidence that they need in order to buy now. And if buyers gain confidence, prices won’t fall, so sellers won’t have to pay. … And it’s natural for sellers to provide the insurance that price protection involves. If they can’t sell their houses, they’re going to end up bearing the house price risk anyway.

Here are some other things sellers could do to keep prices from falling:

  1. Commit to compensate buyers for future appreciation on the home they move out of
  2. Throw in tuition for the neighborhood private schools
  3. Remodel the kitchen