Houses on posts

DIY Network project
Well illustrated playhouse build with some good tips.

Ron Hazelton's Housecalls
Building a platform that sits within a tree, although support comes from posts and a brick wall.

Tom Norian's treehouse
A cleverly designed staircase both supports the house and keeps children using it safe from falls. Built in a California Craftsman style.

Videos

Treehouse time lapse
Clear time lapse video of a small treehouse being constructed between two trees.