When John Jacob Astor died in 1848, he was the wealthiest man in the United States. Like so many people since, Mr. Astor made his fortune speculating on real estate, specifically undeveloped land on the fringe of the city then growing on the island of Manhattan. Mr. Astor did not start out in the industry. He turned to it only after a shift in fashion diminished the prospects for his fur trading business. On his deathbed, his only regret was that he had not bought more. Over the last decade, Americans have taken Mr. Astor's regret to heart. From 1996 to 2005, the residential real estate industry witnessed the greatest run-up in prices ever seen. In 2005, sales of existing homes hit an all-time high of 7 million units. This should have been the best of times for people in the business of buying and selling houses, but to hear most residential real estate agents tell it, the boom passed them by
