The strange field of metamaterials offers some weird optical effects, like cloaking and superlenses. Recently, two breakthroughs in the field, involving programmable materials and gold nano-corkscrews, just made this exotic nano-stuff a little more practical, and maybe even stranger.
Metamaterials are materials engineered to do things nature didn't intend them to do. (We've covered them before.) The most commonly built kind of metamaterials are "optically active" metamaterials, or materials that make light behave in strange ways. They do this by making light bend around tiny folds or dip into nano-sized wells.