There has been a lot of discussion on my blog about the concept of 'over unity' or free energy. Thane Heins claims to have developed a device that produces more than it consumes:
This device is an interesting water heater.
It is a cavitation water heater. What it does is basically bash and mash up water to the point that heat is produced. It's likely that they've come up with an ultra efficient water heater requiring no gas or fuel. It would be electric powered in that it needs electricity to turn an agitator.
They go on to claim that they have measured output of their water heater at 170% efficiency. If this is true, the proof would be simple. Simply hook up the output steam to a steam turbine and use it to power the motor. If the system runs speeds up (a feedback loop) you'd know that you have over 100% efficiency.