This allows you to destroy an Element but leave its contents, including other Elements and text nodes, in its place.

MooTools 1.3 Element.removeTag

Element.implement({
	removeTag: function(){
		var childNodes = this.childNodes;

		for (var i = childNodes.length - 1; i >= 0; i--) {
			if (childNodes[i].nodeType == document.TEXT_NODE) {
				this.appendText(childNodes[i].nodeValue, 'after');
			} else {
				document.id(childNodes[i]).inject(this, 'after');
			}
		}

		this.destroy();
	}
});

HTML:

This text will be in place of the removeMe element.

JS:
$('removeMe').removeTag();

Output:

This text will be in place of the removeMe element.