KaBOOM!

This is a great non-profit organization that deals only with playgrounds, building them, funding them, and making sure playgrounds are everywhere. Their mission: To have every child walking distance from a playground.

Kaboom.org

They also have a PlaySpace Finder with currently over 5000 playgrounds to search from. I have been trying to reach them to work with them on their site. That makes me sound snobbish, but I think the site could use a bit of help. But it's still great.