Sports contain some of the most successful promotional vehicles in the world.
The Super Bowl is annually the most watched event in the country and has become a pseudo holiday.
The NCAA Basketball Tournament consumes the nation for an even longer period. Business analysts actually calculate productivity lost due to people following the tournament when they should be working. (What is the productivity lost by analysts studying the productivity loss of the NCAA tournament when they could be analyzing something else? Boggles the min!)
College Bowl Season (in decline)
The MLB Trade Deadline. I'd suggest that this gets MLB more press and attention than the All-Star game. Live blogs on all the news sites, live programming on both ESPN and NESN. And the bonus is that even the fans of bad teams pay attention to find out how their team will be impacted.