We're happy to share that you can now connect a widget's properties to your site's collections. This makes widgets even more reusable and consumer friendly, letting you use them as rich and complete components without needing any code on the site.
Take a look at these screenshots from a travel site I built. This site has a weather widget and package picker widget and no code at all on the site. The widgets are bound to the dynamic page Dataset, with a "connect" panel presenting all the widget's properties. This creates a destination page which shows the weather for that destination and promotes specific travel packages! Oh, and please pardon the lovely design :-)
Enjoy, and let us know about your App Builder Experience!
The App Builder Team