Making objects invisible by manipulating the surrounding electromagnetic spectrum is just about the coolest thing ever. EVER. EVER. Optical cloaking, and metamaterials in general, is my latest scientific obsession (and possible area of research?!). But as cool as making an invisibility cloak (Harry Potter ftw) sounds, no device has been made that can actually make an object invisible in the visible spectrum, although researchers have been able to create cloaks that work in the microwave range, and have made theoretical designs for cloaks that should operate at visible frequencies. Oh science, how I love thee.