Create Custom Element Property Getters and Setters with MooTools

One of the goals of the MooTools projects is to create very flexible methods by which developers may modify or extend the behavior of given classes. One example of that flexibility is the ability to customize the Element class' get and set methods for specified values.
The default behavior of the get and set methods for an object are to return/modify the given Element attribute. Take the following for example:

var alt = document.id('myImage').get('title');  //returns the image's title attribute text

The above code modifies the title attribute for the given element. Simple, of course, but then MooTools also uses the get/set methods to set and retrieve items that aren't element attributes:

var tag = document.id('myImage').get('tag'); //returns images's tag (img)

The above code retrieves the given element's tag name. How does MooTools do this? Simple: the Element.Properties object. You can set custom get and set handling by adding your desired string to the Element.Properties object. Here's an example:

Element.Properties.yourCustomGetOrSetName = {
 get: function() {
  //your custom programming to accomplish what should be returned...
  return yourReturnValue;
 },
 set: function(input) {
  //your custom programming to accomplish what should be set...
  //don't need to return anything
 },
 erase: function() { //erase works too!
  //programming to erase this
 }
};

Here's the code MooTools uses internally to accomplish the get('tag') ability:

Element.Properties.tag = {
 get: function(){
  return this.tagName.toLowerCase();
 }
};

So how could you use this? You could use Element.Properties to create a parent getter:

Element.Properties.parent = {
 get: function() {
  return this.getParent(); //returns the element's parent
 }
 //no need to do a setter or eraser
};
//.....
//usage
var parent = document.id('myElement').get('parent'); //returns myElement's parent element.

Pretty sweet, no? Have any other items you'd like to see in the get or set methods? Share!