The first urine-powered paper battery has been created by physicists in Singapore.  
The credit-card sized unit could be a useful power source for cheap healthcare test kits for diseases like diabetes, and could even be used in emergency situations to power a cellphone, they say.  
cherwilco: can anyone name even 1 good reason for a product like this that can be outdone by NUMEROUS other portable power sources?
beaglebot: Current biochips need an external reader such as a laser scanner or an external source of power, such as conventional batteries, to perform diagnostic tests. Lee's technology houses both the sensors and the battery on one plastic chip.
YepYep: OK, how 'bout two good reasons then? Huh? Huh?
scilec: Ok, how's this..  
The next time a Japanese porn company is making one of their squirting urine fetish films, one of the actresses can simply piss into a funnel attached to the camera when the batter gets low. That way, then won't have to pause to change the battery. :P
cam78aro88: I can see it now... Piss Powered electric cars... talk about getting pissed on!