AngularJS is a powerful MV-Star framework from Google that has all kinds of neat features, focused on testability and automatic data-binding, it uses a declarative markup style and leverages the strength of the DOM. Yes, the dom is ok at some things. :D
The AngularJS team feels the future of the web is moving more to this declarative style, time will tell, but it definitely makes my life a little less painless.
This example does not really go into the power of AngularJS, but demostrates its simplicity and strong declarative features.
It is a fully functioning contact form that validates every field for being required and validates the the e-mail field for being an e-mail.
It is amazing the amount of functionality you get declaratively, to just do a simple form validation and post.