Adi Zaffran's design is simple but elegant. It's probably dangerous, too. But if you want to create a functional toaster using as few parts as possible, this would be the way to do it.
http://adi.designgroup.co.il/toaster -via Gizmodo | Zaffran's Website
Great interview with the author here:
Also what use is a toaster which only toasts on one side?