Sample application for generating energy from Piezeo Electric Crystal.?
Yes, existance proof of such devices are already available on the street.

Many ignitors work on the priciple of applying a mechanical shock to a piezo crystal, which then produces a high enough voltage to cause a spark.  Look at things like barbecue ignitors.

There are also butane lighters with a long (6 inch maybe) stock.  These aren't for cigarettes, but for lighting fires.  They typically have a gun-like trigger.  When squeezed it opens a valve for the butane to flow, and also activates a mechanical mechanism that slaps a piezo crystal.  The high voltage is transferred by wire to the tip where it causes a spark and ignites the butane.

There are other methods used in these types of ignitors so you have to look carefully, but the piezo method is actually quite common nowadays.