Mike Lanza, who blogs over at Playborhood, did an amazing thing a while back to increase community interaction and kids' play in their northern California neighborhood. He redesigned his front yard into a "family room," with the goal of building a family neighborhood hangout.
Mike blogs about his front yard family room, and you'll be amazed at the innovative additions he's made to his lawn: a 30 foot long outdoor whiteboard, a media system, a fountain, a sandbox, a basketball hoop—and that's not even all. If you're not up for a complete playground in your front yard but do want to encourage outdoor play and neighborhood fraternizing, you might consider adding just one of the elements he talks about.
(Via Active Kids Club; Image: Mike Lanza)