It's no surprise that the number of labs and companies exploring energy harvesting applications is growing by the day.  Think about the endless amount of kinetic energy that's lost during our activities.   

The earliest versions of energy harvesting technologies were attached to what was moving and creating impact:  people.  You've probably heard of designs that can capture energy from walking (attached to shoes, knees, or backpacks) and then produce electricity to power portable devices like phones, ipods, or military communications equipment.  The efficiency of portable electronic devices is improving, making energy harvesting technologies all the more useful and practical.  

Hybrid vehicles use an energy harvesting technology to get power from braking, though I'm surprised the cars still don't use this kind of piezoelectric technology for getting electricity from the wheels, shocks, and engine vibrations.    After braking energy, these seem like the next biggest sources to tap. 

Energy harvesting designs have also expanded to experimental applications for impacted sufaces, like stairs and walkways.  In London and Tokyo, there are pilot projeccts that harvest the energy created by people walking on subway steps and platforms and then power the subway's lights and PA systems. 

Now comes this report from IEEE and Innowattech about capturing energy from road vibrations.  
It seems to me that bridges are ideal places to collect energy, because the absorption of surface motion could also make bridges safer.  Smart bridges with sensors for self-diagnosing stresses are already being built.  Why not collect the stress energy as well as monitoring it?  And why not use the oscillations from traffic noise to power interference technologies (like noise-canceling earphones that capture sound waves inside the plane) for power? 
We need to be looking for big opportunities to harvest energy from our built environment.  If you have ideas, we'd love to hear them.