Honestly, I wonder why they don't bother to put an example on the main page. Looking at the github repo of the project [0] (which doesn't have a folder "example" as well), it says:

    node-webkit is an app runtime based on Chromium and node.js. You can write native apps in HTML and JavaScript with node-webkit. It also lets you call Node.js modules directly from the DOM and enables a new way of writing native applications with all Web technologies.

So I suppose it's about desktop apps ("native" must mean "desktop").

[0] https://github.com/nwjs/nw.js