I’ve been wanting to toy with Polymer for some time, but never had a project in mind. So I decided to just convert one of my smaller github projects into a Polymer component. See:
https://github.com/benkeen/polymer-country-region-selector

It’s uber-simple. It just lets you add country-region dropdowns to your forms. The component automatically updates the region dropdown with whatever values are appropriate, based on the user’s selection in the country dropdown.

Polymer is pretty neat. Very simple, very easy to understand. I’ll totally play with it some more.