The Hyperion Power Module Neighborhood Nuclear Reactor is the size of a hot tub and could provide power for your whole neighborhood! At least, that's what their website claims. Bill Christensen over at Technovelgy points out that other companies have claimed this before, and it came to nothing. But the desire for neighborhood nukes keeps coming back, probably because we've seen them in scifi before - most notably in Heinlein's Friday, where small "shipstones" provide enough energy for a whole space vessel. [via Technovelgy]