Hmmm...embed them in tire treads to replace the alternator?

So if the cost is low, it would be awesome for under road construction. With all the traffic we have in cities and highways, imagine all the power that could be generated. Additionally, it could assist in powering a maglev roadway system.

Could these nano generators if imbedded into electric car tyres produce enough energy to charge the cars batteries as it moved? If so then there would be no need for charging points.

@Cliff Estensen: That would generate maybe a few hundred watts, nowhere near what a vehicle needs to sustain its motion. It would extend the life of the vehicle though, and would be a good addition to solar vehicles.

re; Cliff Estensen
Perpetual motion would be nice but the laws of thermodynamics say it is impossible so at the very least it would be highly unlikely. It would probably produce less energy than the increased rolling resistance would consume. Using the material in the suspension on the other hand promises benefits as would using it in motor mounts as well.

I would place them in the Ocean and let the waves do the generation for on land use

I'm with John Sweet, (you beat me to it) create an artificial reef with these to catch wave action and produce power in addition to creating a safer harbor area.

Artificial reefs have this problem of stuff growing things on it. I would build wave guides that channel the force of the wave into a catchment that once filled dumps the water onto this generator with a self cleaning filter so when the water recedes it flushes the filter. Think of those japanese water feature pitchers they fill up then they tip over

Every time I see one of those huge American flags flapping in a stiff breeze, I think, "That thing should be made of piezoelectric material". Simple and beautiful. Imagine a replacing a huge wind farm with Red White & Blue!

@ Joel Detrow The laws of thermodynamics don't say perpetual motion is impossible. They say it is impossible in a closed system. Earth, however, is NOT a closed system. We are open to the entire universe. Also, earth itself is a very nearly portrayal of perpetual motion at its finest! It's been spinning for the past at least 6 billion years seemingly uninterrupted. We are floating around in a vast sea of energy, just because you're sitting at home on the couch doesn't mean the natural state of things is at rest. NOOO it's ENERGETIC, everything around you is moving at an incredible rate!! Particles on a molecular level bouncing off one another in an unlimited sea of energy which is just constantly changing states. Energy can neither be created nor destroyed; This does not account for the fact that energy is everywhere in unlimited quantities (and don't try saying in a complete vacuum there is no energy, because the Cassimir Effect proves there is always energy). Sorry for the long rant, I had hoped to share some ideas I've had for piezoelectric energy generation to add to the many fantastic ideas already thought up here!
Lining the underside of train cars, the interior walls of engine compartments in all modes of transportation as well as anything with a loud vibrating motor, lining the interior walls of large factories, lampposts in busy cities could power themselves, large buildings in city centres could line the exterior walls (would cut down on wind noise in large buildings), Lining the interior walls of server farms which are extremely loud. With regards to the server farms and engine bays and engines themselves we could build them out a revolutionary new multiferroic alloy called Ni45Co5Mn40Sn10 which converts heat directly into usable electricity via magnetics. Furthermore we could use the floating wind turbines coated with a thin layer of this and a thin photovoltaic skin to provide 3 forms of "free" electricity from just 1 product! Also forgot to mention the footprint required to tether 1 of these is the same size as the footprint needed to tether 50 of these! Thankfully there are countless ways to collect enough energy to power the worlds machines, I haven't even begun to scratch the surface on all the technologies available but can tell you, it was Nikola Tesla's work which sparked my immense interest in this subject.