This doesn't look like much, but it is the ISWEC, the Inertial Seawave Energy Generator, developed by Wave for Energy, a spin-off of the Politecnico di Torino in Italy. It is a very clever electrical generator that converts the rocking motion caused by waves into rotary motion that can generate electricity.
The ISWEC does not; it uses the principle of the gyroscope, which when spinning resists change in direction. The wave motion induces a roll in the gyroscope, which is connected to a generator. The action is completely internal to the hull of the wave generator, and is remarkable to watch; as the hull rocks, the spinning gyroscope rolls around like the spacecraft in the science fiction movie Contact.
In this incredibly cheesy early video (they had a better one at the Fluidtrans show in Milan) you can see a 1/45 scale model in action. They are now preparing to test the 1/8 scale model in the Mediterranean Sea. More at Wave for energy