At http://www.webpop.com http://www.webpop.com we're using JSON Schema as the way to define custom content types behind the scenes. This in combination with Mo

At http://www.webpop.com http://www.webpop.com we're using JSON Schema as the way to define custom content types behind the scenes. This in combination with MongoDB works really well for us. When a user sets up a custom content type, he's actually setting up a JSON Schema for his content without knowing it. And each time a content is persisted we simply validate it against the schema. For now it's just an internal implementation detail, but we plan to expose this through a public REST API at some point.