Top 23 Surprisingly Amazing DIY Pallet Furniture For The Kids I love the idea of the climbing wall and rope climb together!
Backyard Projects For Kids: DIY Race Car Track- this but in a large size filled with pea gravel for rock box/ truck play area
The San Francisco Envy Chain - NYTimes.com. Backyard.
25 Fun DIY Projects for Moms
Scramble Nets for treehouses by Treehouse Life "...a world away from everyday"
Wooden Climb & Slide Frame
This company makes kid rivers for water play.I'm not sure licensing would accept this, but it's so cool!
Incorporate something like this into the climbing area
Cool DIY Backyard Projects To Surprise Kids
DIY swing from an old chair. Love this idea.