app.js

// Prototype version:
// Ti.include('prototype.js');

// Module version:
// Ti.include('module.js');

// Factory version:
Ti.include('factory.js');

var win = Ti.UI.createWindow({
	title: 'Extension Tests',
	backgroundColor: '#eee'
});
win.open();

// Factory Version
var myView = View({ 
	height: 50, 
	backgroundColor: '#ccc' 
});

// 'new' keyword needed for prototype and module versions
var myView = new View({ 
	height: 50, 
	backgroundColor: '#ccc' 
});

myView.add(
	Ti.UI.createButton({ title: 'Click me' })
);

// Add stuff to your new 'view'
myView.foo = {};
myView.foo.bar = 'hello';
myView.foo.bar = 'goodbye';

alert(myView.foo.bar);
myView.coolbeans();

win.add(myView.Element);

factory.js

var View = function(options) {
	function factory() {
		var obj = {};
		
		obj.Element = Ti.UI.createView(options);
		
		obj.add = function(TiObject) {
			obj.Element.add(TiObject);
		};
		
		obj.coolbeans = function() {
			alert('Cool Beans');
		};
		
		return obj;
	};
	
	return new factory();
};

module.js

function View(options) {
	var api = {};
	
	api.Element = Ti.UI.createView(options);
	
	api.add = function(TiObject) {
		api.Element.add(TiObject);
	};
	
	api.coolbeans = function() {
		alert('Cool Beans');
	};
	
	return api;
};

prototype.js

function View(options) {
  this.Element = Ti.UI.createView(options);
}

View.prototype.add = function(TiObject) {
  this.Element.add(TiObject);
};

View.prototype.coolbeans = function() {
	alert('Cool Beans');
};

Nice addition from @iskugor - http://pastie.org/2799391

function Window(options) {
this.Element = Ti.UI.createWindow(options);
}

Window.prototype.add = function(TiWrapper) {
if (TiWrapper && TiWrapper.Element) {
this.Element.add(TiWrapper.Element);
}
};