Climbing pegboards are fantastic exercises for building forearm strength and hand grip. They're the perfect workout for rock climbing and bouldering, or really any sport that requires upper body strength. Gyms don't often feature climbing peg boards.
Shed with playhouse on top. now I love this idea. Makes twice as much use for one space. And just think the bigger the shed you have the bigger a playhouse. Depending on how big the shed is you could do two sides. One for girls one for the boys.