The Panorama House by Moon Hoon offers built-in home theater stadium seating (and a slide for kids and adults alike):
The focal point of this Korean residence is the central multifunctional area, namely the wooden staircase which integrates a slide, bookshelves, reading nooks, and even cinema seating oriented towards a projection screen.
Images: Moon Hoon
Weekend DIYs: 10 Wood Molding Projects for the Home
Monica & Austin's Charming Bungalow
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Ercol Bar Stool
True Greek Recipe: Paximadi Bread Salad with Tomatoes, Feta and Capers
True Greek Recipe: Paximadi Bread Salad with Tomatoes, Feta and Capers
No hand rails! Would never pass county code where I'm from, but love it anyway.