I'd like to nominate private subviews as a pattern.
(function(){
var myPrivateView = Backbone.View.extend({...});
app.views.Foo = Backbone.View.extend({
/* use myPrivateView somewhere in here */
});
})();
It's a good way to break a view into logical sub-components, while still only exposing one overall view to the world. Really just a variation on data hiding and encapsulation.