Is it possible to use Kinetic energy to power small devices?
~ People are making vibration coupling backpack type units that produce in the few Watts range.

~ A typical Chinese squeeze light when operated frenetically will give about 1 Watt. After 5 minutes of use at that level your hand drops off or feels like it has.

~ A properly build hand squeeze power unit could make more like 5 Watts at the same level of effort.

~ A properly built hand crank unit with reasonable throw -  say handle at 150 mm radius will make 10 Watts at reasonable effort. and 20 Watts with rather busy effort. At the 10 Watt level you could do it for an hour +

~ A properly designed pedal unit (many aren't) can make 50 Watts at a level where an only somewhat fit person could do it for an hour, 100 Watts at a level where a moderately fit person wishes they were fitter and more if you are a sports enthusiast. People with sports gear usually make claims to higher power levels than I usually measure. I can do 500 Watts pedalling for about 10 seconds but then need to die for 10 minutes or so. 

~ Shaker torches are probably somewhat below hand squeeze lights in power.
A properly mounted hand crank should be able to be mounted to operate as you walk.

~Piezeo is OK but is usually VERY low power. Newer higher Wattage versions can be bought for money. 

~If you wear a windturbine on your cap it can be made to spin as you walk and will make a few milliwatts. If you mount a 1 metre diameter WT on your cap they will certify you - but power out at a fast walk can be  a Watt or few. 

~Foot fall and leg bend offer much power.

~ Work = Force x distance.   = F x d
 Power = work per time = F x d / t

~ You can work out heel strike force, travel etc for an in shoe alternator. 

~ Anything using hot and cold will produce very very very close to zero power.
 Carnot efficiency = (Thot-Tcold) / Thot
 Real efficiency = Carnot by say 25% if lucky.