TV Site Viewer lets you test tvOS applications that are written entirely in TVML, with no server-hosted JavaScript. All the dynamic behavior is implemented by JavaScript included in the application bundle, with absolutely no external dependencies.
This is more than enough functionality to implement product catalogs, information kiosks, and even simple media library interfaces. If your server generates TVML dynamically, the sky is the limit.
You can use this for rapid prototyping of new TVML applications without writing any code at all, getting most of the work done before you even create your Xcode project!