The National Association of Realtors' convention trade show has shrunk in square footage from mind-bogglingly gigantic to merely large. That may be a consequence of this year's weak housing markets or a sign that the concept of a trade show itself has become out-moded in the Internet age. The too-bright artificial lighting, junk food and temporary booths complete with cheesy games, chinzy giveaways and always-on-their-toes salespeople seem old-fashioned in comparison with the advances of technology. Yet the show goes on in all its lavish excess. One exception this year was Google, which had only a modest-sized booth in a relatively far-back location. But that modest presence was belied by the mob of Realtors who congregated around the booth.