Vaadin has a high quality component set for building mobile and desktop web applications in modern browsers

Ready to use Polymer elements in GWT projects

Modular implementation of Material Design for Mithril.

Polymer and web components for Ruby on Rails

Polymer Web App for The Web Platform Podcast

GDG chapter page using polymer (donated by GDG Twin Cities)

A client/server Dart application using Polymer and Firebase.

Yeoman generator for scaffolding Polymer apps

Useful filters for Polymer

Express and Polymer scaffolding using Yeoman

General discussion and support for web components.