Artist and blogger Joel Henriques of Portland, OR built this delightful playhouse for his twins. It features a simple, modern design, non-toxic paint and varnish, a chalkboard wall, and a surprisingly spacious interior!
Utilizing a small strip of cement on the side of their house, Joel built this simple playhouse with a plexiglass window for natural light, 2x2's for framing, and a metal roof. There's also a small light inside the structure for night lighting. It's surprisingly spacious and stylish inside, especially for a children's playhouse. See Joel's write up at his blog Made by Joel.
(Images used with permission from MadebyJoel)