Hobie has several kayaks which are powered by a unique pedal-operated drive system which frees the user's hands from paddling. The patented Mirage Drive system operates by using two sails underwater which 'flap' much like a penguin's wings. As the sails move from one side of the craft to the other, they change shape to provide propulsion to the kayak on each pedal movement.
Advantages of a Mirage Drive system are that the user has hands free for fishing, and that the boater's powerful leg muscles can be used for propulsion, enabling longer trips with less fatigue.
Disadvantages of the Mirage system is that there is no way to go in reverse (without inconveniently flipping the entire drive) and they fact that the drives can be damaged if care is not taken in shallow water.
In 2006 Hobie introduced an upgraded "Turbo" version of the mirage system that can be retrofitted onto the drive that gives the user a larger sail area and thus generates more power.
For more information about the system, go to The Hobie Website.
For an interesting catfight about the 'pedal vs paddle' debate, wikipedia's kayak session (generally staffed by super snooty kayak purists): http://en.wikipedia.org/wiki/Talk:Kayak#Pedal_kayaks_are_NOT_kayaks