pool with slide waterfall grotto cave by vancedover, via Flickr
Beach entry swimming pool.
Love this. I would swap out the sand for outdoor play mats. Maybe raise a bit higher for a kid's picnic table and water tables. Storage for their bikes, etc.
Climbing Wall/Playhouse built into the corner of the fence. (Make it so that the bottom would be a place to store bikes & lawn equipment)
Garden gym equipment - pull up, dip & monkey bars, climbing wall and ropes
Kid's Tree Deck! cool take on a tree house
Landscaping Natural Playspaces for Children: Tips, Inspiration, Project Ideas (from Mummy Musings and Mayhem)
Cubby Houses | Cubbies House | Fort
diy treehouse / playhouse plans. Wish we could build one big enough like this for kids....who doesn't love a treehouse???
Cubby house ideas