I get it – to introduce someone to enhancing progressively with JavaScript, you need an example that is simple yet complete enough to explain the design and implementation process: Identify core experience & enhancements, group enhancements, what to implement on server & client, how to apply enhancements etc.
I just find it hard, not to say impossible, to contrive an example that has practical value, good code while also teaching the architectural/design thinking of progressive enhancement.