NEW YORK (AdAge.com) -- The naming-rights business in professional sports, which hit a peak in the late 1990s, isn't as robust as it used to be. In the most recent case, as the Major League Baseball season begins this week, the Houston Astros are still looking for someone to replace bankrupt energy company Enron Corp. as the naming-rights holder to its stadium. "The doom has occurred," said Brandon Steiner, of Steiner Sports Marketing, Larchmont, N.Y. "The hits, like Enron's bankruptcy, take away from the franchise and the value. In essence, teams are starting to realize that they're sharing their name...