MooTools Element.unsetStyle and unsetStyles (idea from @keeto)

Element.unsetStyle.js

Element.implement({
	
	unsetStyle: function(property){
		if (property == 'float') property = (Browser.Engine.trident) ? 'styleFloat' : 'cssFloat';
		property = property.camelCase();
		delete this.style[property];
		return this;
	},
	
	unsetStyles: function(properties){
		properties.each(function(property){
			this.unsetStyle(property);
		}, this);
		return this;
	}
	
});