The housing slump has been painful for millions of people who work in real estate or recently bought a house. For Patrick Killelea, however, this year has been one long victory lap. Mr. Killelea, a 41-year-old software engineer, has long preached that it makes more economic sense to rent than buy homes. He recalls shouting "Wow!" when he heard about September's 9.7% drop in prices of new homes. "I didn't want to gloat," he says. "But then again, maybe I did." For years, Americans who refused to buy real estate at what they considered excessive prices were ribbed for failing...