National Backyard Games Week is May 18-25, 2009. I found some great articles with ideas to celebrate this fun week:
Outside Games for Toddlers - Celebrate National Backyard Games Week
Take it Outside! It's National Backyard Games Week
Philadelphia Family Entertainment Examiner: Celebrate National Backyard Games Week
You can also find 175 more games in our book, Great Group Games - and they're all zero prep ideas! If you use the "Going Deeper" questions at the end of each game, you'll also be 'playing with purpose' - using the games to build character, relationships, and leadership skills.