Cheap solar dish that melts steel.

Parabolic solar collectors are nothing new.

The geeks at M.I.T. have created one that is small & cheap, though, which IS new...& uber-cool, even if you don't instantaneously ignite 2x4s by sticking them into the focus like the students did.

Basically a source of concentrated energy that is far cheaper than equivalent photovoltaic panels, you can point its energy at water to make steam to drive a turbine, heat a house, cook, whatever.