var Fader = new Class({

	item: 0,
	delay: 1000,
	elements: null,
	interactive: false,
	
	initialize: function(opts) {
		for(var key in opts) {
			this[key] = opts[key];
		}
		
		this.elements.each(this.setDefault.bind(this));
		
		if(this.interactive) {
			this.elements.each(this.makeInteractive.bind(this));
		}
		
		this.fadeIn();
		
		setInterval(this.swap.bind(this), this.delay);
	},
	
	fadeOut: function() {
		this.elements[this.item].fade('out');
	},

	fadeIn: function() {
		this.elements[this.item].fade('in');
	},
	
	swap: function () {
		this.fadeOut();
		this.item = this.item + 1 >= this.elements.length ? 0 : this.item + 1;
		this.fadeIn();
	},
	
	setDefault: function(el) {
		el.set(this.tweenable, this.min);		
	},
	
	makeInteractive: function(el) {
		el.addEvent('click', this.swap.bind(this));		
	}
});

usage:
	new Fader({
		delay: 1000,
		elements: $$('h3.blurb')
	});

Mootools: Simple Element Rotator

JavaScript