Independent Natural Resources Inc of Minnesota has been testing a a "point absorbing" wave energy converter designed to extract a small amount of energy from a portion of the wave front as the wave passes by called the SEADOG both in a Texas A&M wave pool and of the coast of Freeport, Texas.
Here is a slide show of the installation of the prototype in the Gulf.
From the company website:
As the buoyancy block moves down in the trough of a wave it draws the piston downward through the piston cylinder. The downward movement draws water into the piston cylinder through the intake valve filling the piston cylinder chamber. As the next wave lifts the buoyancy block the water within the piston cylinder is under pressure and is expelled through the exhaust valve. Each cycle of the buoyancy block rising and falling, drawing in and expelling water, is called a stroke. Each stroke of the piston causes the water to be pumped from the piston cylinder in a regular manner.
The video below shows a prototype pump.